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Berichte des Forschungszentrums Jülich
3744
Annua Repo t 1999
Institut für Kernphysik and COSY Research
EDITORIAL BOARD:
Prof. Dr. G . BaurProf. Dr. D. FilgesProf. Dr. K. KillanProf. Dr. R . MaierDr. P . von RossenDr. FL SeyfarthProf . Dr. K. fiste ichProf . Dr. J . SpethProf . Dr.
StröherandProf . Dr. H . Freiesleben, TU Dresden
Cover picture
The outer part of the ring detector of the Time-of-Flight spectrometer (TOF) is shownwhile being in its final assembly stage . lt consists of three lavers of schfiliators, twohaving spirally shaped elements with opposite curvatures and a layer with straightelements. The !arge number of segments results in a high spatial resolution andtherefore excellent vertex reconstruction . The high symmetry of this detector togetherwith its high angular resolution and (arge solid angle make it an ideal tool forpolarisation measurements . TOF was the first external experiment to performmeasurements with a polarized beam from COSY . Details are described in articles ofthis report .
Berichte des Forschungszentrums Jülich ; 3744ISSN 0944-2952Institut für Kernphysik Jül-3744
Zu beziehen durch : Forschungszentrum Jülich GmbH ZentralbibliothekD-52425 Jülich Bundesrepublik Deutschland02461/61-6102 . Telefax : 02461/61-6103 e-mail : zb-publikation fz-juelich .de
Preface
This report lists the 1999 activities of the
jointly performed with our partners of CANUand colleagues from other universities and international laboratories as well as experimentsthat
scientists have carried out at external research facilities.
The focus of the accelerator development was an polarized be s . With the beginning of theyear, TOF was the first external experiment to be mn with polarized protons. During thecourse of the year the number of polarized protons accelerated to the flat-top was raised to2. 109, gaining one order of magnitude in intensity compared to the previous year . A newtuning technique has been developed to more efficiently reduce the influence of thedepolarizing resonances . lt allowed to substantially improve the preservation of polarizationduring acceleration. At this point, we gratefully acknowledge the strong support by the EDDAcollaboration whose detector was the key for this accomplishment . External proton beamswith a pulse length of 1 gs were developed to provide the Basis for target-moderator studies bythe JESSICA collaboration which will investigate the underlying physics to optimize futureneutron spallation sources. To relieve the situation with regard to the tight floor space aconcept was worked out for a new external beam line to the so called East Hall of thecyclotron building . This half could harbor besides others the planned TETHYS experiment.
The basic research in connection with the European Spallation Source was further advanced.The NESSI collaboration completed a whole series of experiments concerning the targetgeometry and target material as well as neutron and charged particle production eross sectionsand multiplicities . In parallel investigations for a superconducting alternative to a pulsedproton linac for the spallation source were performed. A superconducting fest cavity has beenprepared by the industry for delivery and first tests at CERN verified the compliance with theoriginal main specifications.
The TOF-collaboration investigated, among other things, the bremsstrahlung in proton-protoncollisions using the first external polarized proton beam at a momentum of 800 MeV/c . TheTOF-detector acted in this measurement simultaneously as a precise polarimeter due to itss e rical structure and large acceptance . The A-production was studied at excess energiesof 15 and 40 MeV. A clear signal for the rHneson was extracted in a prelirninary analysis . Thecomponents for the TOF-calorimeter, that will extend the capabilities of this detector, werecompleted.
The study of the p d 3He reaction by GEM revealed an unusual forward/backwardpeaking of the angular distribution in comparison to the threshold data which demands furtherpolarization measurements for clarification . The measured cross section data of the GEMcollaboration for the reaction p d ---3. 3He rc° bridge the gap between the near threshold dataand those in the A-resonance region, but are not theoretically understood as yet.
C0SY-11 continued its successful investigation of open and hidden strangeness by studyingsingle meson, K+K-, and K+-hyperon production at their respective thresholds . Measurementsfor the production of ri,
with a deuterium target have been started .
The analyzing power excitation function measurements for p-p elastic scattering up to the endenergy of COSY were completed by the EDDA collaboration and first data of spin correlationcoefficients at two energies were taken applying a polarized beam onto a polarized atomiebeam sarget.
At two energies dose to threshold MOM0 was able to collect now in total 4000 K+K- eventsdue to high extemal beam currents resulting from an optimal COSY extraction efficiency of80%. A prelinünary analysis revealed, contrary to the lt+ 7V measurements, a distribution thatis consistent with phase space but also carries a clear signature of the 4 -meson on top.
The ANKE spectrometer inside the COSY ring collected at various energies a wealth of dataconceming the K+-meson production in proton-12C collisions . The collaboration succeeded inproving the production of K+-mesons well below the NN-threshold . The collected data willalso allow to deduce angular- and momentumsdistributions.
The investigations of the experimental groups were complemented by activities of the theorygroup. A meson-theoretical model for meson-nucleon scattering has been developed andsuccessfully applied for energies up to 1 .9 GeV. The Roper resonance N* (1440) is claimed tobe generated dynarnically by pionsnucleon and two-pionsnueleon interactions. A new fieldtheoretical formalism suggested by Weinberg was significantly improved and shown to givequantitative agreement with nucleon-nucleon scattering and deuteron data . The non-vanishingtransverse spin asyrmnetry observed in polarized deep-inelastic scattering was explained byunitarity effeas . A destmaive interference mechanism was suggested as the reason for thesuppression of Z o-production near the threshold . The pion structure function has beencalculated in the color dipole approach to deep inelastic scattering in good agreement with theexperimental data from HERA.
The EUROBALL- collaboration has been concentrating on the investigation of dipole bandsin 142Gd. The analysis of the data taken with the large solid angle y-detector array incombination with the 4tt charged partide telescope ISIS suggest the Interpretation of thaseexcitations as magnetie rotational bands.
The work presented in this report is, of course, also the result of the dedication of ourtechnicians and engineers . Equally important were the support of the service groups andthe infrastmaure of the Forschungszentrum Jülich . As always, the students working on theirdiploma and respectively, on their Ph .D-theses had a substantial impact on advancing theresearch at COSY. We also gladly mention the friendly collaboration with CANU and themany outside users which is the foundation of the cormnon success.
Our gratitude extends to the advisory committees who have been helping us in the oftendifficult deeisionsmaking process . Indispensable as well was the support which many outsideusers obtained by the B F and through the FliE-program of the Forschungszentrum Jülich.Last but not least we are deeply indebted to the board of directors of the ForschungszentrumJülich for their commitment to the research program of COSY .
INSTITUTE FOR NUCLEAR PHYSICS
Forschungszentrum Jülich GmbH
D-52425 Jülich, Germany
Managing director :
Prof. Dr. R. Maier
Experimental Nuclear Physics 1, director :
Prof. Dr. K. Kilian
Accelerator division, head of the :
Prof . Dr. R . Maier
Experimental Nuclear Physics M, director :
Prof . Dr. H. Streiher
Theoretical Physics, director :
Prof. Dr. J . Speth
CONTENTS
1 .1
Experiments at COS
Status of the Technical Development o ffhe
Developments 0n the
forTOF,~, .,^,,, ~~,^^, .,_,~^6
More about Strangeness Production 81 COS
,,._~,, .^ ~,~, '7
An
for COS
_~~ ~_,~^, .~ .,^, ^~,_,,,^,,, .^8
Efficiency deterrrünation of the üeQt%oU0 detector COSYnDs ~ .~ . .^ . .,~, [)
First Po arization Measurement a1 the ~ . . .l8
q-00eQ0n pmduchon 81 COS
.,~ ^ . . . .~ .~ .~ ^ .~ . .~ .- .~ .,~- . .~~^^ . . .1 1
New Developments in the COSSystem 12
First Results with an
Status Report /~~J~]~ . .~ . .-~ ^ ^ . .^ . . .~~. .~- . .~--{~
Development of a
Procedure 81ANKE.~^ _~ .~~~,^ .~ .~ .^ .16
Calibration of the ANKE side detector b` a ' ' mass
~~^^^~^"" .^" .18
for background suppression a~ ^,^,,_,,~~^^, .,,,~_~19
The
for the ANKE-Experiment a1COS
Luminosity Determination a1 ANKE with Spectator
Detector Tests 8t the Tandem-Accelerator in Cologne for +heSpectator Identification a1 the ANKE-experimen . .~ 22
^f the branching ratio a~ lt^q hK + --«
Production of a~-DOes0Qs in the reaction ppd n ~ nehreshold 25
Possibility U0 search f or m~ -resonances in ~he reaction
ppat
1q pmduction in p + p interactions DeG~ ~6~e
- ^ ~ ~-.~ .~ 77
particle
a~
,,,,,,,^ .^',_,_,,~~ ~,_,_ 78
First Measurements with the
~~Chips f Silicon -1~~--r~
~A of
Evaluation of
for
.~fron ~~ Chips ~ Silicon Strip
Design of a Vacuum-compatible Read-ou Board for theANKE Vertex
PbWO4 as a scintillator
' for a
U1 ANKE/COSY 34
Status of +he
for ANKE 35
The
omic Beam Source for the
^ ^,,~^ . ._36
A
f^rvhe polarized target at ANKE 39
A-production at = 80 MeV
Dt
COSY- 1 1
of
Cross !~~ '~ ~ r theEnergy Dependence "^f the Total
f~~ ~ppReaction cl^se o the Kinematica
of the Pnrnary Production Amplitude for
the pp
Determination of the COSY Proton-Be[0O~ Dimensions by meansof +he C\OSY- 11 Detecfion
~l~Yl~
~~ .
Production of w-Mesons UJ COSY- 1
Near-Threshold 10
Production in
.^ .- .~^ .~^-^`-'48
Missing Mass Resolution in
chold Measurements 49
The Reaction pd _43»«-l0 ~n'\a COSY- 11,,,^,,~,,~,__,,,,,,,, ~ ., .~ .,^ ._,^, .,,50
Efficiency of the
from the COSY- 11 DriftChamber
Deuterium Recuperation for C uster Targets a~
Mes8DPr0dDclion C]0se to
'~}II~~~0!~.~ ~,~ .~- ~ ~~
~~' /uuleo00 Pion~vn Production in r -~~. ..~../X~~&~08D~ ~ ~~
7l Produeton in' the S l Resonance
--~-~e-~~~~me~^ of ~ ~~p~~ ~z~m~rz ~~~akmg ~^ ~^~ r ' d ' ^~' " t+and p+d 'He+7t reactions . .
. 8
Background reduetion methods for Big Kar Y firm dipole yokehole detection
~,^,'__,,,,~ .,,__^,,~,,,, ._ .^~,^~^ .~_,,~,,_ .,^, . .^__,,_,_,,_ . .~,60
The
of Proton-Proton
The Storage CeOfor the EDDA-Experiment 0d
Remub s on Two-Kaon Production D1 MOM0 66
1 .2
Experiments 8I Extemal Facilities
of »he ATRAP-Experi ent a1 AD/CERN 71
Charge state of exo+i`atoIIlQ
from the moleeules N 2 d
On-~~ne contro~ of the Jülich high-precision Bragg crystal
. .~ 73
of the Roper
^~,,,,^,_~,,, ^,_,,,,,,,,~^,, .,,~, . .^ .~~,,75
~.
Investigafion of
Bands in l42Gd h EUROBALL
79
Study of
I%oO]eDt8 of
in
/~~Fro~Ihigh~z&o superdeformed shapes : study of
Pattern Recognition Method for y -R»`
,,,^,,^~ .,^_ R2
Development mfa fast PPADC
.~,,,,,,,,~ ^ ., .^, .,^ . .~-_ . .~-- .~. .~,^ .83
Investigation of ~~~= ratlos and~f.~~n ~f Y~~`~~
n~~ linear polanzam of y raysin 142Gd with
~ . MEDIUM AND HIGH ENERGY PHYSICS
Pimn f~r,v, _
' _ ---~~e presence
virtua _p .~ . .^~ ~~
Construction of the '
'
of fourth
, .91
Virtual photons in baryon ehiral pertubatation theory 92
S
ge vector form factors mf the
Hyperon form
'
t~~ Mandelstam~~ ~~u'
-g inside ---
_-_-g-_ . . . .' . . . .` .^ .--- ., .' ' ~~~~
Chiral unitary '
dxnm
'in f6~
of
. .__~.~,,_0o~^
~
presence
-
of t6ereartion 7t
The nucleon-nueleon '
' fron` effective fielet theory 98
Nueleon properties and the NN i` rera,ti*n in
del- ' . . .l0]
'
^Neutral ~
off deuterium at
Dense QCD: Overhauser 8r BCS P
'Generalized Pions ~" Dense ~~~^,, .^~~ ~ .^ . . .~ ~~^ ~ . .~~^ . .~- .!Ou~~" .
Generalized.
'~~~.~^^~ ~. Den se .~~~~~ . .~ . .~ .^ ~, . . .~,,~. .-.~ .,~~~^^ ^ ~°
chiral
0e0oD-mesO0S-wave l= 1y7
t0meson-0OesoD xnJinteractionsmeson-baryon
'
and final state interactions nf+he -OTD
.~1 H8Neutral ^
polarizabilities
~
Spin
mf+he nucleon 109
Low
with explicit /k/1 232\ degrees
, .110
of the
on a
}2
Nucleon-nucleon FSI
in meson production in
'
.--^~ .-^ . . . . 113effects
(u_ and
in fhe re ' pn --> dM De~~
Near threshold A and 10
in ppproduetion
What '@ *he structure of the Roper
af the ~, ~^ ~, . .! ~ ~
~J~oo `~~^~~/`t.^-/~~~~\^ pN bound state or ~~
res0n@~lce`~^'~'^-~" .'--"^^`~^~^~~U~Q^`~~~~~^~~ `~~~~~
steep'se of spin stmciu1e function g LT = g l +g2
The perspectives of study
in the reaction
o ps ckose to '~~^ .~ .- . .` ~ ~ l~~
Microscopic
mf 10-meson pmduction in
Heavy ~wn
AHeavy
Novel Mechanism for Bremsstrahlung inIon Collisions 125
Bound-Free ~~~~ Production in
I.^' ^
~ .~~~r~m~ . Col1lsl0ns- 1~~.~°
Pionium interacting ^~~+h 1I~~te~ ~ . . .-~ . . . .~ ~~ . . . .^ .^--.-127
mfthe nucleon 128
The GAMS-B NL
,,,, __~___, ._.~^~ .~,~ . .^~~ . ._^~,l38
4 .
AND REACTION MECHANISM
Nm missing isoscalar
in 58Ni: fin al
On the Interrelation Between Ferrnionic and Bosonic Exitations in
. ., .135
Review of the Mechanisms f or
^, ._~ .~ 136
Influence of Damping 0D the Excitation of the Double Gian .__ ._ 1 3'7
COSY Machine Report 143
Polarized beam in C0SY 144
Determination of
in COSY frmrnf6ebroad-band B
^ ^, . .^ . . .~ .^ .^- ~ ~, .^ . . . .` . . .,~, . . .~~^ }46
'm~ High-Intensity Low-Enn arme Proton BeamsPreparatmn
Fast Kicker Extraction a1 C\OSY -^ .^ '~~ ~ . . .~ .~ }49
Preparing a
for Installation a1 COSY 150
Magnets, Alignrnent and New
The COSY
S
., .~ .~ .` .,^ ^^^,^~ . . .~ . . .^ .~~ . .,~~_ . .,153
6. ION SOURCES A BEAM TRANSPORT
Ion Sources at C0SY 157
7. SPEC'l ROMETER BIG
Magnetic Spectrograph BIG
8.
Evolution *fa spallation
': expenment
'
and Monte Carlosimulation
17 1
Neutron ^
ti in thin and t hick W, ~~~~
--- -a-f _ _-_
. .g^
3~*
'.~-dlsIriQut1oDs following dl1ferentintrI-nucle0r-ca8cade-mode}8 ~ ~ .173
Progress on JESSIC/k ~ . . .,~~- .- .,~^ _^__ ~_,, . . .,_~ ..174
Apparatus to '~,,,, ~ ~,, 175
Development
~~
for -h--p . .^~-~~ .^'6
Status of
77
10. ACCELERATORCOMPONENTS
Field-Profile Measurements 2{a 5-G mp Crossed-Spokes Model
,, .~~.}8}
Study for a
for COSY-ESS Linac 184
Beam Loss Studies for the ESS Accelerator Ca plex 185
•
sed Mode Operation of the FZ.l 500 MHz sc Cavity Teststand . . . . 188
Technical Developments
DATA AC UISITI N, ELECTRONICS, S IC N UCTDETECTORS, TARGETS
Semiconductor Detectors and T getr 195
200-Strip Germanium Detector for x-Ray Spectroscopy at theESR Storage Ring
.196
COSY Experiment Data Acquisition and rocessi g 197
Electronics 198
Vl. cie t ic Conneil C0SY 201
VII Advisory Co
'ttees 201
• II. Collaborations 203
IX.
ers
el 213
Publications 223
• Index of' s 245
Exp
_1 °ad on Ph .
s
U ENERGY PHYSICS
a CG
1 .2 Experimen a Externai Facilities
2. NUCLE SPECTROSCOPY
2
1 n Experiments
4
Status of the Teehnical Development of the TOF-Detector
R. Bilger3 , H. Clement3 , J . Daemen2 . K. Däring2 , A. Erhardt3 , D . Filges ' , M. Fleischer2 , H. Hadamek ' , G. Hansen 2 ,H. Kämmerling 2 , R. Klein ' , K . Kilian 1 , J. Kress 3 , C. Mehmer2 , N. Paul ' , W. Renftle 2 , E . Raderburg ' ,
H. Stechemesser2 , H. Wynwich2 , for the TOF-Collaboration1 Institut für Kernphysik, 2Zentralabteilung Technologie, 3 Physikalisches Institut Universität Tübingen
1. The new build "Ring-Detector"
With the new manufactured and assembled "Ring-Detector"first measurements are made . The signals from this pre-cision manufactured high quality scintillator detector are atleast as good as expected and fulfil our expectations.
2. Progress of the "Three Layer Barrel Detector"
The investigations to find out the material properties forbending the over 4 m long scintillator strips are continued incooperation with the ZAT of the FZ-Jülich . A remarkableand important result is : All dimensions of the strip, length,width and thickness are increasing of course when heatingup to the bending temperature but they will not come backcomplete to the previous dirnensions when cooling down toroom temperature . The thickness increase each time a littlebit and the width of the strip becomes smaller . This we haveto take into account when a bending model has to be con-structed.The coefficient of linear expansion is different for the scin-tillator material and the surface material of the bendingmodel . The scintillator slides on the surfaee when heatingup for bending or annealing also when cooling down tomom temperature . If the material combination is incorrectselected the scintillator surface gets a Look of an orange peeland the total light reflection becomes disturbed.The hot air oven which are ordered in 1998 are deliveredand installed to continue the investigations with originallong from BICRON delivered scintillator strips.
Fig 1 : Look inside the Hot Lx Oven
This oven has an inner width of 2 .5m , a clearance of 2 .5mand an inner length of 6m . Inside the oven are two rollers on
rails to mount on the model for bending the scintillatorstrips . To control not only the temperature of the hot air atdifferent points also die temperature of the bending modeland the scintillators are 16 thermo-couples inside installedon long flexible wires . The temperature Tange is from roomtemperature to 250°C maximum . The temperature differ-ente within the oven is in the range between 50°C and 95°Cwhere we have to use it, approximately 1°K . This accuracyis very important for heating up die scintillators to the sof-tening point, otherwise the scintillator strips will be stressedor distroyed.This oven is connected to our cooling water system . Withthis possibility we are able not only heat up the oven withcomputer defined heating ramps also cooling it down bycomputer defined cooling rartips . The heating up, holdingand cooling down procedure is very time consuming so it isimportant for bending a high number of scintillator strips tooptimize this procedure.
3. Energy Detector
The concept of the energy detector has been cleared up incooperation with the University of Tübingen and the ZATof FZ-Jülich . Detail drawings has been made and given todifferent workshops to produce the mechanical parts of it.These mechanical components of the detector are deliveredand only final work at die FZ-Jülich main workshop has tobe made . A mounting stand and a lifting facility has beendelivered too . More than the halve number of die hexagonalshaped scintillators are glued together with its light guides(s . Fig . 2)
Fig . 2 : Hexagonal shaped energy detector scintjator withlight guide.
Members of the University of Tübingen are developing andtesting a ca.littration system for the 84 photomultipliers tocompensate its temperature dependence . The system workswith special stabilized blue colored light emitting diodes toconsider the spectral sensitivity of the photomultipliers.
5
Deve
ents on the Straw Tracking Detector for TOF
D.Filges, R.Geyer, K .Kilian, K.Nünighoff, M.Schmitz
The developments on a very light tracking de-tector based on straw tubes was continued [1].
To achieve higher mechanical stability a module
consisting of 16 straws was glued together in
form of a double layer plane . The deflection due
to the gravitation was measured . This module
shows a deflection of less than 140 p,rn . Such
modules have a high mechanical stability and are
seif supporting . A device was developed to
assemble a double layer plane consisting of 200
straws. This device allows the positioning and
glueing of the double layer plane as shown in
Fig.1 . The straws will be glued together with a
low viscosity cyanacrylat glue (Lochte 408). The
mass of the glue can be reduced by taking
advantage of the capillar action . The possibilty of
resolving the glueing allows to exchange defect
straws . At the moment techniques for mass
production will be developed like wiring and
glueing tools.
A second way of cathode contacting was
developed . The endcap will glued inside the
straw in the way that the straw habe will be
overlap the endcap . Inside this overlap a snap
ring will be mounted. This ring will be kept in
position and contact the cathode just by its
restoring force . The advantage is the easier and
faster way of assembling . To insert the endcaps
much easier into the frame the holes in the frames
will be The concept of the read-out electronic
was advanced. Close to the detector a preamplifier
will be mounted . This preamplifier operates
under vacuum conditions and matches the
impedance between the ASD8B-Chip [2] and the
straw-tobe . The signal will be transfered through
coaxial cables from the preamplifier to the
ASD8B-chip . First prototypes were succesfullytested. This preamplifiers will be Integrated in the
frame construction . Cooling methods for
electronic components in vacuum are presently
studied.
Presently at the ZEL the F1-Chip [3] will be
tested . This chip is a development from the
university of Freiburg and is especially designed
for drift time measuring of straw chamber
detectors for the COMPAS experiment at CERN.The read-out electronic will be integrated in a
dato aquisition system developed by ZEL [4,5]
which is used in further COSY experiments like
GEM, ANKE or C0SY-11.
Fig.I This figure shows the three steps to
assemble a double layer plane . At first
the bottom layer will be glued together.
In the second step each second strawof the top layer will be glued to the
bottom layer . Finally the missing ones
of the top layer will be glued.
References:
[1] K.Nünighoff et ah, A Light Straw Tracker
Detector Working in Vacuum, poster
presentation and proceedings on the
5. Position Sensitive Detectors Conference
in London
[2] F.M. Newcomer et al ., A Fast, Low Power,
Amplifier-Shaper-Discriminator for High
Rate Straw Tracking Systems
[3] G.Braun et ah, Fl - An Fight Channel
Time-to-Digital and Latch Integrated
Circuit developed for the COMPASS
Experiment at CERN, draft version,
University Freiburg
[4] MDrochner, P
thesis,
Jü1-3218, Jülich 1996
[5] P,Wüstner, P
thesis,
University . Bochum 1998
I .Step:
2 .Step:
3.Step:
6
More abouf Strange
The COSY-TOF Collaboration, Ex
The associated strangeness production inelementary reactions dose to threshold is ahing term reseasch program at COSY-TOF.The lüghly granulated TOF detector coversalmost the füll phase space and aliows tomeasure all differential distributions as wellas total cross sections and the A-polarization . Up to now the reaction channelpp K'Ap was investigated at severalbeam momenta fiom 2.50 up to 2.85 GeV/c.MoreoveT there are first measurements ofthe ehwels pp K°E+p, K+E+n.The data of the A-production at 2 .75 GeV/c[1], especially indicate the influence of thepA-final state interaction and give someindication for the influence of N*-resonances, coupling to the KA-subsystem.This shows up in the Dalitz plots and itsprojections oh the mass subsystems, whichis shown for the KA-system in Figure 1.
2
aii
1 .8
EGeV1
Fig. 1: KA-projeetion of the Dalitz Plot of thereaction pp -3 K+Ap at 2 .75 GeV/c and 2 .50 GeV/c
The shift to higher masses can be explainedin resonance model calelilaflohs [2] wherethe influence of the N*(1710) and N*(1720)affects the spectrum in the observed way . Asubsample of the very preliminary data at2.85 GeV/c gives further confidence for theinfluence of the discussed N*-resonances.The shape of the projection an the KA-subsystem is different compared to thephase space also at this momentum. Againthere is an enhancement corresponding tothe square of the N*-resonance at 1 .71 GeVwhich has the strongest branch into the KA-subsystem. The complete sample of about
"t events at 2.85 GeV/c will give oredetailed information oh this toi*.
htion at C0SY-T0F*
ent E7 (Spoke sen: W. Eyrich)
The first measurement of the channels pp -3,K°E+p, K++n dose to threshold simulta-neously perfonned at 2.85 GeV/c will leadto samples of a few hundred events . InF' 2 is shown the spectrum of theeconstmeted E+shyperons for a 20% sah-sample of the ehanne! pp -4 K°rp.Obviously the interesting reaction c bewell separated from the baekeround mainlyconsisthig of events of the charmel ppK+Ap, which have a similar signature and alive times larger cross sectian.
.o
eoo,-oM----i-
t3o
20 :--
15
10
5
0.2
0
0 .6
0.8
1
1.2
1
1.6
1 .8 2ass(GeVI2
Fig.
Speetram of the reconstructed E +-hypemnsfor a subsample at 2 .85 GeV/c
In '99 the stop deteetor of the TOFapparatus was completed by ring and barrel.With this version schematically shown inFigure 3 a high precision study of thehyperon production will follow . For thefuture the measurements will include apolarized beam and in a second steil also apolarized target.
Fig . 3: TOF '99 version
[1] R. Bilger et al ., Phys . Lett . B 420 (1998), 217[2] A. Sibirtsev et al ., Phys . Lett. B 421 (1998), 59
su
by B F
FZ Jülich
75 GeV/c2.50 GeV/c
7
An external po
eter for COSY-TOF
A.Wilms* for the COSY-TOF Collaboration
In December 1998, the first polarized proton beamwith a momentum of 797 MeV/c was extracted atCOSY. In order to supervise the polarization onlinean eatemal polarimeter has been designed and con-strueted at Bochum.lt cmmists of four detector modules which are ar-ranged at an angle of 90' with respect to eaeh otherand of an internal 5 mm thick 12 C target with adiameter of 27.8 mm. The center of the target is
'tisted in the beam center and the four modulesare arranged concentrically and perpendicular to thebeam-direction . Bach polarimeter module has onestartsseintillator and a stop-region which is made upof four plastic-scintillators (50 mm x 50 mm x 5 mm)connedted to one photomultiplier . In order to obtaina first separation of pions produced in the internal' 2 C target from the quasi elastie scattered protonsof the analyzing reaction pC -+ pC, a 50 mm thick
. cuboid between the start and the stop detectorregion is used. To ensure dissipationless detection ofthese protons in the stop scintillators read out in co-incidence with the start region the 5 mm thick startscintillator has a basal plane of 10 mm x 10 mm . Be-tween the four stop scintillators at a distance of 5mm to each other three 5 mm thick pieces of 1are ar-ranged to guaxantee a final and proper separa-tion of protons and produced pions . In order to keepthe system as variable as possible the support of eachmodule allows to setup different seatteringsanglesin the reaction-plane applying to the beam-direction.The beam polarization can be calculated using the
well Imown maximum value of the analyzing-powerAy of the analyzing reaetion pC -4 pC (to keep thestatistical error as low as possible) at a scattering an-gle of 19 = 10, 5° (lab .) (Ay = 0.6) and the measuredasymmetry ey of the recorded counting rates:
NL - NR pz Ay,ey -o ( 1 )NL + NR
withN L : wahre of the left hand side measured counting-rate andNR : value of the right hand side measured counting-
To elirninate detector asymmetries (e .g. differentacceptances of the polarimeter modales) the so ealledsuperasymmetry has to be used
Bist . for Experimental Physics 1, Ruhr-Universität Bochum
NLtN RL - NL!. NRf P AyNRteY NLt
+ NL-1- 'withNL(R)t : left hand side (right hand site) measuredcounting rate for beam polarization "up" andNL(R)4, : left hand side (right hand site) measuredcounting rate for beam polarization "down".In Deeember 1998 the pol
eter was installed be-hind the quirl detector of COSY-TOF in order tomeasure the asymmetry of the counting rates of thequasi elastie scattered protons with two opposite po-larimeter modules a time adjusted in the reactionplane . The other two opposite modules perpendicu-lar to this plane were used for monitoring the spändirection of the primary incident protons of COSY.The beam polarization being calculated from themeasured counting rates of the polarimeter has tobe compared with the polarization extraeted o nefrom the elastic proton-proton-scattering detectedwith the ring in order to scrutinize the fimctioningof the polarimeter.The elastie pp-scattering has an analysing power ofA y = 0.4 at a Iah angle of 19 = 15 .0', which is usedto calenlette the polarization. The calibration of ringand barrel detector is essential to get a proper resultfor the polarization of the elastie scattered protons inthe ring, because these protons have to be identifiedby their time of flight and the coplanar hit pattern inring and barrel. only. Therefore, this method of cal-culation is not advantageous for online analysis. The
me anadysis of the first polaldzed externalCOSY-beam gave the following results (calculated withoutbackground suppression):
43% ± 2% (ring data)Pzinax =-- 40% ± 5% (polarimeter data
So the extemal polarimeter can be used to estimatethe beam polarization online without many calibra-tions to be made.
References
Gerald G .Ohlsen, Nuelear Instruments And Meth-ods 109 p. 41-59, North-Holland PublishinCo . (1973)
8
Efficiency determination of the neutron detector COSYnus*
L. Karsch , A . Böhm ' , K .-T. Brin
, H . Freieslebe , G. Sun
and L . Demirörs 2 , W. Scobel 2
The detector COSYnus
presented in previousantiefes [1] . lt consists of 10cm thick, 10 cm high and1 or 2 m long bars of scintillator NE 102 A, which areread out an both sides by photomultipfiers . The neutrondetection efficiency was determined using two of fourDresden modules (each modul consists of three barswhich are 2 m lang) and the Timesof-Flight-speetrometerTOF at COSY.One of the difficulties when measuring the efficiency isthe determination of the total neutron ffux . The methodof assoeiated paxtieles is one possibilty to overcomethis problem . Here, this method was extented to thethree-body reaction p + d -.+ p + p + n . The two protonswere detected in the TOF and the neutron direction iscalculated from the velocity vectors of these protons.The efficiency of the neutron detector is inferred from theratio of detected neutrons to those hitting the detector.Because of the three-body nature of the reaetion, thisyieids the efficiency over a range of neutron energies.For neutron energies Ty, > 110 MeV a sample of 57neutrons was detected during 18 h with a beam of about105 protons per second. This is shown in Fig . 1, wherethe applied cut in Tn. as well as the detector dimensionsin polar angle are indicated by the box. The averageneutron energy for the Chosen intervall is 160 MeV.A polarized beam was used, so that the reconstructedneutrons exhibit an angab: distribution which is notazimuthally symmetric (Fig. 2), but constant over thedetector region indicated by the two lines. The resultis compared to a simulation using the ende MODEFF(Fig. 3 and table) . This code is suitabie for neutronenergies between 1 and 300 MeV and for small deteetors.The simulation underestimetes the measured efficiency.This may be due to the restriction to certain reactionchannels in the ende and the neglect of Iight transport inthe detector . The data at 14 .7 MeV was collected duringan experiment at the TU Dresden using the method ofassociated particles in the reaction d +T --+ et + n . Bothmeasurements are described in [2].
Energy in MeV 14, 7 160
Threshold in MeVpe 3,4 10,5 3,4
Efficiency
Simulation in %
23, 1±6r2
22,0
7, 4± co) :
6, 6
12, 4±
10,3
supported by BMBF and FZJCOSY neutron pectrometer
i Institut für Kern-- und Teilchenphysik, TU Dresden2 1 . Institut für Experimentalphysik, Universität Hamburg
References[1] A . Böhm et ah, IKP Annual Report, FZ Jülich 1997[2] L . Karsch, Diplomarbeit, TU Dresden 1999
Fig. 2 Azimuthal distribution of reconstructed neutrons.
>, 0 .30000 0 .25
0
0 .2
0.15
0 .1
0.05
00 20 40 60 60 100 120 140 160 180 200 220
kinetic energy in MeV
Fig. 3 The result of the measurement in comparison toa simulation (threshold 3 .6 MeV7,e ) . The data point at14 .7 MeV represents the measurement at the TU Dres-den .
50
100
o
200
250
300
kinetie energy in MeV
Fig . 1 Distribution of energy and polar angle of the pro-duced neutron as reconstructed from the two protons.
detectorregion
is
via
5
0 2 , , n n j n n: 1 n n 1 , 1 n
0
50
100
150
200
250
300
350
azimuthal angle in deg
9
First Polarization Measurement the TOF-Speetrometer
K .-Th. Brinkmarml for the COSY-TOF collaboration
In January 1999, a first attempt was
e to e-tr a polaxized proton beam out of COSY into theexternal TOF experiment at a beam momentum ofPc = 797 MeV. Terdmical details on the beam prop-arties as well as the setup are given eIsewhere in thisreport [1] . The TOF in its current version for low-energy investigations consists of the end cap with thecentral » Quirl» hocbascope, the outer Ring hodoscopeand the harret section together with the Rossendorfstart detector . The setup covers a Iarge &achan of theforward hemisphere, thus allowing the detection of ejec-tiles from leas than 3° up to 75° polar angle.The main experimental focus of the expeaiment wasthe investigation of the pp bremsstrahlung near thepion threshold. A very preliminary analysis of aboutone Edith of the total dato sample allows first conclu-sions conderning the average polarization and the time-integrated luminosity achieved . To this end, the datoare scainned for elastic pp scattering events which con-stitute 99.99% of the cross sectim at this momentum.Elastic scattering is identified by two eoplanar hits inthe detector with an opening angle close to 90° . Theratios (Nt - Nt)/(Nt +N4), where the direetions of thearrows denote the spie orientation of the beam, as afunction of azimuthal angle for 3' polar angle bins werefitted with a cosine function . The asymmetries, whichare given as the amplitude of the fit function, obviouslystrongly dopend on the polar angle of the proton. Fig.1 shows a summary of these results in terms of pp aua-lyzing power compared to the SAH) solution SM99a.nd dato from the literature [3] . Here, the asymmetriesmeasured with TOF have beiert normalized assuming anaverage beam polarization of 38.5%.Figure 2 shows the eross sechans normalized to the re-sults of the forementioned SAID solution . By compar-ing clN/dfl to the predieted ddjdfl we direetly extractthe integrated luminosity to be 0 .3 nb-l . Applyingsmall corrections for acceptanees, this is the overallcross section normalization also for other reaetion chan-nels . Applying this normalization, the p° total crosssection ran be estimated from the missing mass peak tobe about 1 .5 !ab with a large uncertainty due to accep-tance correetions of the order of 20% . This value agreesnicely with the available literature on neutral pion pro-duction in pp collisions near threshold [4] . The analysisahned at not only the extraetimt of p° but also ppilf
is in progress.
astitut Für Kern- und Teilchenphysik, TU Dresdensupported by BMBF and FZJ
eneesE. Kohlmami and H . Stockhorst, this report.
[2] SAID, R . A . Arndt, Phys . Rev . C56, 3005 (1997),available on the internet under http ://said-hladesy.de[3] B. v . Prezwoski et al ., Phys . Rev . C58, 1897 (1998).[4] A.Bondar et ah, Phys . Lett B356, 8 (1995) .
-0 .5
10
20
30
40
50
60
70 80/ deg.
Fig. 1 Ilifeasured asymmetry of elastic scattering as a
function of polar angle compared to a SAID solutionand dato from the hterature. The TOF dato have
Wen n9rnelized- e texe fir *Wie-
70 8012 / deg.
Figi 2 Measured angulax distribution of elastic ppscattering compared to the SMD solution.
-o.
-0 .4
10
r7-meson production at COSY-TOF
S . Marwinski for the COSY-TOF Collaboration
The r1-meson-production in proton protoncollisions was measured at the COSY-TOF-spectrometer in February 1999 . lt was exam-ined with unpolarized protons at 2 .025 GeV/c and2.1 GeV/c . These experiments continue the mea-surements of the C0SY-11 collaboration [1] withhigher beam momenta . For this the large TOFsetup was used consisting of Quirl, Ring and Barrelas stop-counters, the Rossendorf start-counter anda liquid hydrogen target . The distance betweenStart and Quirl was 3 .14 m and the diameter of theBarrel 3 .1 m.For the calibration of the detector two planar two-body reactions can be used : pp -3 ppel as t (crosssection of 22 .1 mb, nearly half of the total crosssection) and pp -4 dir+ . Both can be reconstructedgeometrically from their two hits in Quirl or Ring[2] . At the used beam momenta the excess energyis 424 MeV or 450 MeV and the angular limit forthe deuterons in the Iabssystem is at most 18 .4°.Due to the different velocities of the pions anddeuterons the energy loss in the scintillators differsup to a factor of 4, so that pions and deuterons canbe seperated and distinguished from the pp elasicevents.
Fig.l : Longitudinal vs . transversal Momentumof coplanar two bit events geometrically reconstructed.Also included are the kinematical predictions of elas-tic protons, deuterons, pions at a momentum of 2 .1GeV/c and the angular acceptance of Quirl(10°) andRing(26°) . Barrel not yet fmafly calibrated!
Figure 1 shows longitudinal versus transversal mo-mentum of planar two hit events geometrically re-constructed . The dir+ sevents agree well with thekinematical curves . Due to the not completed Bar-rel calibration one sees deviations in 0 from the
predictions for elastics events, in which one of theparticles hits the Barrel . The Barrel is only used toselect planar events . For that the 9 precision in theBarrel is not important . The elastic events in theQuirl are missing, because the second coincidentproton is too Iow in the energy and to high in theangle and cannot be detected by the Barrel in thisregion.The ri-mesonsproduction pp -4 pp") was measuredat excess energies of 15 MeV and 40 MeV . Theangular limit of the reaction protons is 9 .7° for thelower excess energy, so that both protons hit theQuirl . The time calibration of the detector wasdone with elastics and checked by dir+sevents. Thetime resolution of the detector is 330 ps . Protontime of flight and the Crack direction allow to de-termine the proton 4-vectors . For the ferst steps ofanalysis only the neutral risdecays (branching ratio70%) were considered by selecting two hit events,where both detected particles in the Quirl are pro-tons. Figure 2 shows the missing mass spectrum of5% of the measured data . A sharp ri-peak at 0 .299GeV 2/e4 is seen with a resolution of ar = 1 .2%.
Fig .2: Missing Mass Plotfrom two proton hits in the Quirl at a beam momenof 2 .025 GeV/c (15 MeV excess energy) . The massresolution of the r"-peak is 1 .2%.
References
[1] J . Smyrski : Near-Threshold Meson Produc-tion in Proton-Proton Collisions Phys . Lett . B474 (2000) 182
[2] M . Dahmen: Das Flugzeitspektrometer anCOSY, Jülich 1995
um
11
New Developments in the C0SY Cryogenie Target SystemS . Abd Ei-Samad *, N. Dons, K. Kilian, R. Klein, H. Lands
We optimized further the properties, workingconditions and reliability of the cryogenic LiquidH2/D2 target [1, 2] and control system.A gravity assisted heat pipe system [3] has been
developed with the target liquid as transportmedium. The combination of heat pipe and thintarget cell provides stable working conditions withminimum density variation and minimizes inactivematerials to less than 10g in the 32cm Iring standardsetup compared with a 600g solid cooper rod in theprevious system . Heat pipes with a nominaldiarneter of 16mm combined with the target cell areroutinely used with H2/D 2/CH4/N 2 (Fig . 1).A comparison of the cool down times from roomtemperature to operating temperature with heat pipeand the so far used solid heat conductors is shownin Fig . 2. The heat pipe saves more than 80 minutesin cooling down time. Also the time needed forheating up to room temperature is correspondinglyshorter. Figure 3 shows a comparison between theeffective thermal conductivity of hydrogen heatpipe-target cell and that of solid conductors-targetcell with the same dimensions as the heat pipe . Thehighest values are obtained as X eff = 100 W/cm.K,which in comparison with the thermal conductivityof copper (2ooj =14 W/cm.K) is 7 times betten Thehigh thermal conductivity of the heat pipe stabilizesthe target temperature with in ±0 .05 K in the rangeof liquid hydrogen/deuterium. Figure 4 shows theeffect of heat load an the effective thermalconductivity of the hydrogen heat pipe . Itsconductivity increases with increasing heat load.This heat pipe could transfer more heat load . Thelimitation here comes from the cooling capacity ofthe cryo-cooler.Figure 5 shows a comparison of the thermalconductivity with methane filling of the heat pipewith solid heat conductors . The highest values are
obtained as Ä.eff = 200 W/cm.K, which incomparison with the thermal conductivity of copperat liquid methan temperature (,c„ = 4 W/cm .K) is50 times bettenFrom all experimental results we can conclude thatthe amount of heat that can be transported as latentheat of vaporization in a heat pipe is usually anorder of magnitude Iarger than that which can betransported as sensible heat in a conventionalmetallic system. The heat pipe can thereforetransport a lange arnount of heat with small size andweight.
NRC, AEA, Egypt
Fig. Photograph hei pi w_ target ct`'
Fig. 2 The target cool down time with solidconductors and with heat pipes.
A heat pipe of Im length and 16mm diameter hasalready worked . A 2m heat pipe system is underdevelopment for future TOF experiments.
300
250
200 1 -
50 0
Gend( Tann
0
20
40
60
80
100
120
140 160
Time (min .)
12
o -1--
13,5
14
14,5
15
15,5
16
16,5
Operating temperature (K)
Fig. 3 Comparison the effertive thermalconductivity of hydrogen heat pipe-target cellwith that of solid condurtors .
Fig. 5 Comparison the effective thermalconductivity of et ne heat pipe-target calwith that of solid conductors.
References:[1] V. Jaeckle et ah, "A liquid hydrogen/ deuterium
target with very thin vdndows" Nucl . Instr . AndMeth. A349 (1994) P 15-17.
[2] A. Hassan et ad .," The target area of the externalCOSY experiments" Nuclear Physics A626(1997) P 435-438.
[3] A. Faghri "Heat pipe science and technology"Taylor & Fr cis USA 1995.
Fig. 4 Effeet of hehe load an the effeetive thermalconductivity of 112 heat pipe .
13
First Results with an Extracted Polarized Proton Boom
E. Kahlrnann * for the COSY-TOF CollaharationH . Stockhorst for the COSY-TEAM
Polarized protons have been accelerated within theCOSY ring already for some years and great progressin crossing the various depolarizing resonances hasbeen made [1] . Here a report will be given anfirst results obtained with an extracted j-beam at
pbearra =0 . 8 GeV/r.
Using the method of stochastic extraction polar-
[3] A. Lehrach, PhD . The~4t) Univ . Bonn (1998) p . 47
ized protons in spills of length 10 s followed by a5s Break were focussed towards the COSY-TOFspectrometer consisting of Rossendorf stahl letector,barrel and endcap with quirl and ring . P
ned andbuilt as an azimuthally symmetric dett -?
ss, is ide-ally suited to act as a polarimeter . Elaste atteringevents from the p reaction could b i >d in co-incidence and for all azimutha.l e-angi~ in the polarangle range. t = 16°-26° . Identifying . astic scatter-ing events by their coplanar hit pattern and addi-tionally requiring appropriate signals in the corre-sponding QDC modules the beam polarization P as afunction of was deduced from the expression P -4 y
= (N t - N l )/(N t + N 1 ) with N t , N 1 being the co-incidence yield for protons with spin up and down,respectively . For the analyzing power A y in the cov-ered angular range an average value A z,=0.35 wasassumed [2] . In the top part of fig . 1 spill-averageddata are shown ; with the ring-wedge number being
proportional to e the data follow a cos-distribution
aoas expected . An average polarization P=41. .6% is
found, which is significantly less than the > 80% de-
70
termined with the low energy polarimeter in front
l
60of the COSY ring . When dividing the spill (of totalength 10 s) in smaller pieces and determining', ;> po-larizationfor each of these sections in an otlewiH- ;se
identical rnanner one arrives at a time d i tehd<l nt
40
plot which is shown in the bottom pari of fig . 1.Apart from some low entries below t=1 s, the polar-
ization P drops gradually from a maximum near 60%
20
down to values aroz.tnd 30%, an eifert which is still
under deba.te . From the accelerator point of view
t6
this decrease may be due to the extraction proce- 0Bure . when applying the method of stochastic ex-traction the horizontal tune is rnoved from below to-wards the extraction tune Q=3 .666 thereby crossingthird order depolarization resonances [3] . Their in-fluence gets the more harmful the longer a spill ischosen . Further work is in. progress.
Supported by BMBF and FZ .Nilich ..
"Inst . für Kern- und Teilchenphysik, Technische Universität
Dresden
References
[ l ] A . Lehrach et al . t 2th lot . Symp . an High EnergySein Physies, Amsterdam (1996)
[2] R.A. Arndt et al ., Phys . Rev . C56 (1997) 2005
•r
•0
30
9_
•
cl
31 .67±
-4o er P2
:3 .38 ±
F3
.1083 f
1071
?0
40
60
so
100
Ring Wedge No.
pp_elastic
. e
0
4
5
6
7
8
9
10
Time in Spill (s)
Fig. l :
top :
e-distribution of spill-averaged i-polarizatron deduced from elastie scattering events whichwere recorded in the 6-range 16°-27° ; bottom : time-resolved polarization P obtained when breaking the still
ections of roughly equal lengths (see text).
14
Status Report ANKEM . Büscher and K . Sistemich for the ANKE callaberation
Four weeks of beam time have been ailocated to ANKE at COSYin 1999. They were used for the measurement of the momentumspectra of forward emitted K4--mesons from proton-carbonreactions (pC-tiK4 X) and for the preparation of studies of the NN-
final state interaction via proton-proton cotlisions (pp-edit,pp->pntt» . The measurements of the double differential crosssections d 2irs, / d12dp
K+have been performed at projectile energies
Tp between 1 .0 and 2 .3 GeV, hence below and above the free NN-
threshold of 1 .58 GeV . The studies at high energies served fortests, optimization of the detector setup and normalizationpurposes with comparatively high intensities of K 4-mesons . Theyhave also been used for the development of data-analysisprocedures which need to be very sophisticated since, atTp«1 .58 GeV, K 4 --mesons have to be identified in presence of an
up to 106 times more intense background of protons and pions.The measurement of the K4 -momentum spectra at Iow energiesdown to Tp = 1 .0 GeV is expected to help understanding thestrangeness production process inside the nucleus . The studiesare described in detail in a contribution [1] to this report.
The experiments in 1999 have also deepened the understanding
of the properties of the spectrometer and of its detection devices(see e . g . [2, 3]) . Prerequisite for the success of the experiments,in particular at small Tp, is a constant luminosity during each COSYcycle which allows to make optimum use of the rate capability ofthe ANKE detector system. For the K4-meson studies a diamond
target (500 pg/cm 2 , triangular shape 20 mm Iong, 2 mm width at
the top) was placed in a fixed position. The COSY beam wasaccelerated below the target and then steered upwards . A speelalproeedure has been developed [4] for a beam-target overlap whichguarantees constant counting rates in the ANKE detectors . The
luminosity amounted to (1-2) - 1032/cm2 •s . The limiting factor in the
acceptable rate was the multiwire proportional chamber (MWPC) 1at the exit window of ANKE, see Fig . 1 . lt can accept rates of up to10 6/s .
D2
Fig . Moor plan of ANKE.
A second prerequisite for the study of the subthreshold K4 .i
produeton at energies down to Tp = 1 .0 GeV is a dedicated fast
trigger system [5] . lt aliows a suppression of background with theuse of the time-of-flight information from the 23 stau detectors atthe exit window of the spectrometer magnet D2 and 15 stopseintinators which are patt of telescopes at the focal surface of themagnet (see Fig . 1) . Only events for which the time-of-fiight fits toK4--mesons are accepted . Plans and protons can be suppressed inthis way as well as with the energy-loss information from the
AE detectors which are patt of the focai surface telescopes [1].The trigger system aliows a reduction of the data by a factor ofabout 400 to a background-to-kaon ratio of 104 . The fast ANKEdata-acquisition system [6] can handle the reduced rate and stare
the data an 'arte .
A third means to identify kaons provides the decay of themesons . They are stopped in the
detector of an individualtelescope or the Cu plates behind it (Deg . 2 in Fig. 1) and theycannot be observed by the veto detector . Their decay produttscan, however, be deteeteil in the veto counters with a delay whichis characteristic for the 12 .4 ns mean-lifetime of the kaons . Cuts anthese delayed events provide an additional very efficientbackground suppression [1], at a reduced detection efficiency.
in August 1999 the cluster-jet target for protons and deuteronsbunt by a group at the university of Münster has been implementedinto the ANKE setup [7] and tested in a one week's beam time . ltshowed the envisaged performance with a luminosity of aboutlo29/cm2 is [8] . lt will be used for the study of elementary processesIlke the a -meson produeton in proton-proton interactions [9] andthe measurement of the deuteron break-up in pd collisions [10].The target chamber has been constructed in such a way that eitherthe gas-jet or a strip target can now be used.
Besides the research at ANKE and the analysis of the obtaineddata, the work an additional detectors and target systems hasbeen continued . The detectors for forward (FD) and backward(BD) emitted ejectiles, e . g . from proton-induced deuteron break-up, are almost complete. The avaiiabie parts have been tested"parasitically" during the K4 -runs.
Design studies for K-detectors and tests of prototypes have beencarried out [11] . These detectors will be placed at the side of thespectrometer magnet which is oppasite to the exit.Measurements of K4 -light particle eieineidenees with thedetectors and a scintillator hodoscope (SD) have begun . K4 -dcoincidences, which are predicted [12] to be characteristic for thetwo-step mechanism in the subthreshold K4-production processare in preparation . Tests and design studies have also beenperformed an near-target detectors [13], both as spectatordetectors for tagging pn reactions in the processpd dp, pX(X = and reconstruction of vertices inexperiments with a storage-cell target for polarized nudei . Suchdetectors have also been used for luminosity monitoring by thereaction pd-epd [8] . Furthermore, the construction of a compactphoton spectrometer, matte of PbWO 4 , is under study [14].
As far as new targets are concemed, the development of the pellettarget at the ITEP, Moscow, [15] and of the atomic beam source(ABS) for polarized particles (callaboration Erlangen, Gatchina,Jülich, Köln) [16] have advanced considerably . The campteden ofthe devices is expected by the end of 2000 . in the case of thepolarized target the activities will now conpentrate an thedevelopment of the storage cell target, the use of which willincrease the effective thickness of the target provided by the ABS.
Referenoes:1. H . Junghans et ai . : Contribution to this report, p . 162. G . Borchert et al . : Contribution to this report, p. 183. G . Borchert, M . Büscher et ai. : Contribution to this report, p . 194. Design by D . Prasuhn, H . Schneider, Aecel . Div. of the IKP5. R . Schleichern PhD Thesis, RWTH Aachen, 19966. M. Hartmann, PhD Thesis, Universität zu Köln, 19977. H . H . Adam et al . : Contribution to this report, p . 20B. S. Barsov et ah : Contribution to this report, p . 219. M . Büscher et al . : Contribution to this report, p . 2410. V . I . Komarov et al . : Proposal COSY-20, 1992 and 199911. H . R. Koch et al. : Contribution to this report, p . 2812. A . Sibirtsev et al . : Z . Phys . A 347 (1994) 19113. A . Mussgiiier et al ., Contribution to this report, p . 30 ff14. V . Hejny et al . : Contribution to this report, p . 3415. W. Borgs et ai . : Contribution this report, p. 3516. H . Seyfarth et ah : Contribution to this report, p. 36
15
Development of a K + -Identification Procedure at ANKE
H. Junghans, V. Koptev l , M . Bücher
Data on K+ production in Proton-carbon collisionswere taken at the spectrometer ANKE [1] at proton-beam energies from 2 .3 GeV down to 1 .0 GeV. At1 .0 GeV the K + mesons are accompanied by a back-ground consisting of protons and pions which ex-ceeds the K + production rate by a factor of 106 [2].This background can be suppressed by applying cutson time of flight (TOF) between the scintillationdetectors, on energy losses in these detectors andon the track information from the multi-wire pro-portional chambers (MWPCs) . In the following thedata-analysis procedures as well as the number ofidentified kaons in the telescopes are presented.A first analysis for K + identification was carried outat 2 .3 GeV beam energy where the cross-section forpion production is only about 10 2 times higher thanthe one for kaon production [2] . The cuts for kaonidentification are defined at this energy. Since theANKE setup stays the same for changing energiesthese cuts can also be applied at the other ener-gies. Figure 1 shows the TOF spectrum at 2 .3 GeVbeam energy between the start counters and the stopcounter in telescope #11 . A detailed description ofthe setup of the telescopes can be found in [1, 3].According to the angular acceptance of ANKE onlystart counters #8-18 are accepted in coincidencewith telescope #11 [4] . The unshaded distribution in
NI600
400
200
0
200
300
400TOF [44pslehan.]
Figure 1 : TOF spectrum between start counters andstop counter #11 . Shown are the distributions afterall the cuts for kaon identification have been applied(shaded curve) and without any Cut . The arrows indi-cate where the cuts for kaon identification are placedin the TOF spectrum.
Fig . 1 represents the events without any cuts on sein-tillator or MWPC information . The shaded distribu-tion contains the kaons remaining after applying allcuts . The most important cuts for kaon-identificationare explained belowAt turns out that around 80% ofthe particles reaching the telescope are pions (peakat channel 250) and protons (peak at channel 390)stemming from the target . The remaining 20% aremainly protons scattered on the vacuum chamberor rescattered on the pole shoes of the D2 magnet
(pB in Fig . 1) . Due to their broad momentum distri-bution scattered protons are almost homogeneouslydistributed in the TOF spectrum. The arrows in thespectrum indicate where the cuts for kaon identifica-tion are placed . Nearly all pions and protons from thetarget but only a part of the scattered protons can besuppressed with this out . The scattered protons se-lected with this cut have a narrow TOF distributionwhich is equivalent to a narrow momentum distribu-tion. Due to the ratio m p/mK+ Irr 2 the mean mo-mentum of these selected scattered protons is aroundtwice the momentum of the kaons . With the use ofdegraders in front and behind the AE counter the dif-ferent range of particles in the ANKE telescopes [1]is exploited : kaons are stopped at the end of thecounter or in the second degrader ; thus, their energyloss in the AE counter is maximized since their Braggpeak lies inside this counter . Scattered protons passthrough all the components of a telescope and theirenergy loss is significantly smaller than Chose of thekaons as seen in Fig . 2. With the additional cut indi-cated in this figure more than 95% of the remainingscattered protons can be rejected.
200
400Energy-Lioss 2iE [ehan.]
Figure 2 : Energysloss spectrum in the AE counterof telescope #11 . The shaded curve represents thedistribution after all the cuts and the clear curveshows the distribution of the scattered protons insidethe cuts indicated in Fig .1 . Pions and protons fromthe target are suppressed by the TOF Cut from Fig . 1.
A strong indication that particles of the shaded dis-tribution in Figs . 1 and 2 are kaons is the spectrumof time difference between the veto counter and thestop counter of the same telescope as presented inFig . 3 . As mentioned above kaons are stopped at theend of the dE counter or in the second degrader anddecay with a mean lifetime of 12 .4 ns mainly intomuons and pions . About one third of the isotropi-cally emitted decay particles reach the veto counterof the same telescope . This happens with a charac-teristic delay with respect to prompt particles . Thespectrum in Fig . 3 exhibits an exponential decay witha slope of 11 .8±2 .0 ns in good agreement with themean lifetime of kaons . If a eilt in this spectrum is
N
100
50
0
16
placed 1 .3 ns after the peak of prompt particles back-ground events are suppressed by a factor of 200 . Theadditional loss of K + events caused by this cut isonly 10% [5].
1200
1400
1600dt(Veto,Stop) [44pshchan.]
Figure 3 : Distribution of time difference between theveto counter and the stop counter of telescope #11at Tp = 2 .3 GeV after all cuts for K+-identification.
After applying all cuts on the scintillator informa-tion some background events mainly scattered pro-tons are still present in the spectra . At Tp = 2.3 GeVthe number of this background particles is negligi-ble in comparison to the number of identified kaons.However, at low beam energies the scattered protonsbecome dominant in the spectra . The use of MWPCinformation helps to basically eliminate this remain-ing background . Particles from the target have char-acteristic vertical angles which can be reconstructedwith the information obtained from the MWPCs.Figure 4 shows the distribution of the difference be-tween the expected and measured vertical angle atbeam energies of 1 .2 and 1 .0 GeV after all cuts onscintillator information are applied . The K + mesonsare located in a narrow peak around zero sitting on anearly constant level of background [5] . The numberof identified kaons (shaded area in Fig . 4) is obtainedafter linear background subtraction in these spectra.
Figure 4 : Distribution of the difference between theexpected and measured vertical angle t9 in telescope#11 for a) 1 .2 GeV and b) 1 .0 GeV proton-beamenergy [6] . The shaded area represents the numberof the identified kaons.
The momentum bite of a telescope increases withdecreasing telescope number . The described cuts areless efficient for lower telescope numbers so that theremaining background increases and the kaon peaks
in the spectra corresponding to Fig . 4 are not seenanymore. Therefore in the current stage of the data-analysis the K + intensities can only be determinedat 1 .2 GeV for momenta >200 MeV/c (telescopes> #3) and at 1 .0 GeV for momenta >250 MeV/c(telescopes > #6).Figure 5 shows the numbers of identified kaons in thedifferent telescopes at 1 .2 and 1 .0 GeV. The numbersare not yet corrected for different detection efficien-cies of the telescopes and for decay in ffight . A firstanalysis of the detection efficiencies indicates thatthis number varies between 10 and 20% for the dif-ferent telescopes. lt should be noted that the shadedspectra presented in Figs . 1-3 were also obtained ap-plying MWPC cuts on particles from the target (seeFig. 4) in order to suppress scattered background,thus, to obtain clearer spectra.
600
t 1 .0 GeV, 100 h1 .2 GeV, 24 h
400 -
4200
0175
250
325
400
475Momentum [MeV/c]
Figure 5 : Number of identified kaons from the car-bon target in the different telescopes at 1 .2 GeV and1 .0 GeV proton beam energy without correction fordifferent detection efficiencies of the telescopes andfor decay in flight . Error bars include statistical un-certainties from background subtraction.
Summarizing, a method of kaon identification hasbeen developed . At ANKE kaons can be identified indifferent telescopes down to the lowest measured pro-ton beam energy of 1 .0 GeV . In the next beam timein February 2000 measurements will be performed todetermine the detection efficiencies of the differenttelescopes . With this knowledge double differentialcross-sections for K+-production will be obtained.References:
M . Büscher, K . Sistemich, contribution to thisreport, p . 15
H . Müller, Z . Phys. 339, 409 (1991)
A . Franzen, Ph.D . Thesis, Universität zu Köln(1996)
[4] M. Büscher et al ., IKP Ann . Rep. 98, FZ Jülich,12 (1998)
H . Junghans, Ph .D. Thesis, Universität zu Köln(1999)
S . Barsov et al ., Prise . 8th Hit . Conf. on HadronSpectroscopy, Aug . 24-28, 1999, Beijing, China
1 St . Petersburg Nuclear Physics Institute
13 [0 .15 0/ehan .]
N
[ 1 ]
[2]
[ 3]
[ 5]
[ 6]
Calibration of the ANKE side detector by a missing mass method
G .Borchert , M.Büscher , S .Dymov', A .K ach ar avaa ' 1) V.Komarova, V .Kurbatov° , H . Müller°, S Xaschenkoa
Reconstruction of ejectile 3-momentum needs a pre-cise knowledge of the spectrometer description, in-cluding the geometrical arrangement of the spec-trometer elements and 3d-maps of the magnetic fieldin the whole spectrometer spare . The direct mea-surement of all these characteristics provides ratheraccurate momentum reconstruction . However, uncer-tainties of these data and possible systematic errorsusually do not allow to reach the limiting accuracyof the spectrometer.For this aim one can use a calibration procedure, inwhich some kinematical parameters of a chosen cali-bration process are compared with the reconstructedvalues found from experimental data . Then, the ob-served rather small deviations of the calculated andobserved values of the kinematical parameters can beminimized by a fitting procedure of some free param-eters of the setup . They should be treated as effectivevalues taking into account all the unobserved devi-ations of the used setup description from the realsetup.We used the reaction pp -+ dir+ for calibration us-ing the MWPC positions as free parameters in orderto fit the deuteron mass from the measured ejectilemomenta . Data were Laken at 9 different beam ener-gies (corresponding to ir+ with 9 different momentahitting 9 different telescopes from 6th to 14th) usinga CH 2 target . Background was subtracted with theCH 2 -C difference method.In previous analyses [1, 2] a systematic deviation ofpion momenta and missing mass from the expectedvalues was noted . This deviation can be explained byan inaccuracy of the position of the Side MWPC's.lt was noticed that the position of MWPC2 is prob-ably known worse than MWPC1 because the latteris mounted rigidly to D2 . Assuming PC2 is strictlyperpendicular to the median plane of D2, there arefour variables defining the position of PC2 : the co-ordinates of its centre xo, yo, zo and the orientationangle a . The vertical coordinate can be determinedfrom symmetry requirements : all the distributions oftracks, coming from the target, positioned in the me-dian plane should be symmetrical relative to the me-dian plane of D2 . So, in fad, there are three remain-ing parameters to be determined : xo, zo and a.In the following this procedure is described briefiy . In
Fig .la the found missing mass m, 2 for the reactionpp ei+ dir+ is shown as a dashed line for differentvalues of the initial energy (different r +-momentum)for the measured PC2 position . The reduced missingmass is calculated by the formula:
[(Ebeam + mr, E ir) 2 - (A. -
300 dir+ events per beam energy were used to fitthe parameters xo, zo, a by x 2 minimization with the
program FUMILI [3] . the geometry of PC2 werecorrect, M2 would be equal 1 independent of pbeamFor the selected values 42 , an' during iterationm, for every event from the i-th telescope, we foundthe pion 3-momentum by a Runge-Kutta method.Then we calculated the average (4) j for this tele-scope according to formula (1) and used the obtainedset of (Mi) i for the caIculation of x2 .As initial values we took the values measured for theJuly 98 beam time : x 0 = -78.3 cm, zo 50.4 cm,
= -7.01° . The vertical coordinate yo = 0 was fixedduring the fit . The values of the parameters foundafter the fit are: x 0 = -80 .59 cm, zo = 51 .52 cm,a = -7.14°. In Fig.la we show the values of (M x?)'after fit as solid line . In Fig .lb we show the differencebetween values of the kinematical (emission angle 0°)and measured pion momenta (6 < 3°) before andafter the fit .
J -M-J--1--1--h--n-",b-,
-ldo o-I--M-Mnh-noggto :. .e)-a
e
--j---h-Igh--1--nn-- :'°.i
-.
--- -
-nidoM:M.. .onn-.
JDnmax, Mag ie
max, Mev / c
Figure 1 : a) Missing mass mr2 as function of g+ mo-mentum; b) difference of expected and measured ir+momenta . Solid for fitted values, dashed for primary.
From the both figures we can see that with new posi-tion of PC2 the both characteristics agree with kine-matical values . The results can be recommended tothe ANKE collaboration for further use.References:
S.Dymov et al ., Internat report of ANKE collab-oration : "Mass processing of data an calibrationreaction pp -4 dir+ at ANKE", January 1999.
S.Dymov et ah, Internal report of ANKE col-laboration : " Investigation of possible reasons fordiscrepancy in reconstructed momentum value" ,February 1999.
S. Dymov et al ., " Constrained minimization inC++ environment", JINR report E10-98-318,Dubna (1998).
JINR, Dubna, Russia*HEPI TSU, Tbilisi, GeorgiaIKHP, FZ-Rossendorf
*) Partly supported by WTZ grant RUS-666-97.( 1 )2
U
0 .998
0 .996
g :
--
--
--- -
0 .994150
200
250
300
150
200
250
300
[ 2 ]
[3]
18
Offsline methods for background suppression at ANKE
G .Borchert, M .Büscher, S .Dymov a , A.K acharavaa ,b , V.Komarov a , V.Kurbatova S.Yaschenko a
In a previous analysis [1] we used the so-called y'ycriterion for suppression of background events notcoming from the target but rather steming from scat-tering at the pole shoes of the spectrometer dipoleD2 . A particle behind D2 is described in the XYplane by the equation y = ay . x + by , y' ay . X de-notes the direction horizontally perpendicular to theundisturbed COSY beam and Y the vertical coordi-nate (see also [2]) ; y is the height coordinate of thetracks on the middle plane of MWPC1 (x = -49.5cm) . The y'y criterion is based on the fact that fora given height y the value y' varies in only a nar-row interval for events coming from the target . Thus,we can expect quite a good separation of the "true"events (from the target) from the background in ay'y scatter-plot . In Fig.la we show such a scatter-plot for data of run 126, beam-time July '98 withlimitations (shown as two lines) imposed by this cri-terion . These limitations were chosen using GEANT-simulated events, so that y' values for the given yvaried by not more than 2 RMS from the average.Obviously, the y' value for a track coming from thetarget depends not only on y, but also on the (x,z)coordinates in this plane (middle plane of PC1) be-cause these coordinates are related with the tracklength in the magnetic field and vertical defocusingat the boundary of the magnetic field . We chose thisdependancy in the following form : y'
+
y + C2 z + z' + C4 . y 2 + C5 y . z + C6 y z' +C7 z2 + C8 z z' + C9 z'2 ) . The coefficients C,., areto be found by a fitting procedure using GEANT-simulated tracks emitted from the target.
p, can
Figure 1 : a) y'y scatter-plot for real data from run126 ; b) Ay' distribution for simulated backgroundevents and real dato.
In Fig.lb (unshaded histogram) the distribution ofdifferences Ay' = yG ack - VforTnula is presented, wheregrack is found by track reconstruction and isformulacalculated . One can see that the background eventsfrom the real dato. form symmetrically positionedwings and are clearly distinguished from the peakof "true" events.We investigated the effectiveness of the both (y'y,Ay') criteria, main background sources, and com-pared the methods . The effectiveness of each cri-terion was estimated first with GEANT-simulatedtracks coming from the target . For the y' y criterion
we used the mentioned above 2 RMS cut, and forthe !IV criterion we used gy'l < 0 .05, which pro-vided approximately equal results for the both meth-ods (y'y method - 1 .2%, Ay' method - 1 .0% rejectedtarget events) . For the same cuts we got the followingfraction of rejected experimental events : y'y method- 23% ; Ay' method - 33%. For the comparison ofthis methods we simulated several background dato,samples . As main background sources we consideredthe flange (construction material at the connection ofvacuum tobe with D2, points F1 and F2 in Fig .2a,band D2 magnet poles (points P1, P2) .
F1
Figure 2 : Sketch of the different background sources.
The background events were generated in a wideinterval of angles and momentum for the magneticfield value corresponding to conditions during run126. The values in the following table show the frac-tion of background events that passed these criteria.
Vertex point F 1 2 P Py'y 76% 33% 9% 3%Ay' 58% 1.9% 1 .6% 0 .7%
In Fig .lb (shaded histograms) we show Ay' distribu-tions for tracks originating at the dipole and flange.Note that distributions from dipole and flange arepositioned in the region of the background wings ofreal data. One can see that the position of the max-ima of the wings corresponds to background sourceswith its origin far from the median plane.lt is seen that the Ay' method provides essentiallybetter background suppression than the y'y crite-rion. Comparison of simulation with the real eventsshows that the main background sources are locatedfar from the median plane, and can be suppressedessentially by the Ay' method.Referenhes:
[1] G .Borchert et al ., IKP Ann . Rep. 1998, FZ-Jülich, (1999), p .13.
[2] M .Büscher and K .Sistemich, contribution tothis Ann. Rep., p .15.
[3] S .Dymov et al ., Internal report : "Analysis of run125, 126 ANKE beamstime", Dubna, July 98.
JINR, Dubna, Russia *b HEPI TSU, Tbilisi, Georgia*) Partly supported by WTZ grant RUS-666-97.
Bei
19
The Cluster
get for the ANKE-Experilne at C0SYH.-H. Adam*, A. Khoukaz*, N . Lang*, T . Lister*, C. Quentmeier*, R . Santo*
Cluster beams are of growing interest for aecel-erator experiments . Compared to other gas targetsIhre gas-jet beams, they offer a number of advantageslike a spatially well defined target beam with a ho-mogeneous density distribution.
For experiments at the ANKE installation atCOSY, a duster target was built in 1998 by theIKP at the University of Münster . To study reac-tion channels under different conditions, the ANKEfacility allows to move the scattering chamber to-gether with the magnet D2 relative to the remainingCOSY magnets . Therefore, for the design of the tar-get installation it had to be taken into account thatthe vacuum stages have to follow the movement ofthe scattering chamber.
The main task of the target is to provide hydro-gen duster beams to study elementary protonsprotoninteractions, but also other gases like deuterium, oxy-gen or xenon can be used . The design takes advan-tage of extensive studies on duster beam production,which have been performed in the framework of op-timizing the performance of cluster targets for stor-age ring experiments [1] . The design is based on theduster target for the COSY-11 installation, whichpreviously was built up in the IKP at Münster [2, 3].A sketch of the mechanical assembly of the ANKECluster target is shown in Fig . 1.
The installation of the duster target at theANKE target place TP1 was performed within fourdays in August 1999 . At the end of that week thecomplete target installation was successfully set intooperation and a hydrogen cluster beam was shotthrough the ANKE scattering chamber.
The control system of the target installationbases on a Linux PC-system equipped with ADC's,DAC's and I/O-cards to monitor the status of im-
48149 Münster, Germany
Figure 1 : Sketch of the duster target for the ANKE experiment at COSY.
skimmer
skimmerstage
,
Laval
2nd collimator
scattering
Ist beam
2nd beam
3rd beam
turbo pump
nozzie
stage
chamber
dump stage
dump stage dump stage
Cluster beam du P
portant target components like pumps, shutters andvalves and to display pressure values in the differentpumping stages.
In September 1999 first data have been taken us-ing the duster target at the ANKE facility. Duringthat beam time a stable hydrogen duster beam withan oval shape of 6 x 15 mm 2 was produced. Theachieved areal density is estimated to be - 5 - 1013atoms/cm 2. In addition, data have been taken us-ing a deuterium cluster beam, providing neutrons astarget for meson production in proton-neutron scat-tering. To minimize operation costs during furtherbeam times using the more expensive deuterium gas,a recuperation system was developed and build in theIKP at Münster . This system was tested during pastbeam times in 1999 at COSY and will be regularyused in the future [4].
References
[1] A. Khoukaz, T. Lister, C . Quentmeier, R.Santo,and C . Thomas, Eur .Phys.J . D5, 275 (1999)
[2] H. Dombrowski, D . Grzonka, W. Hamsink, A.Khoukaz, T. Lister, R.Santo, Nucl . Phys. A386, 228 (1997)
[3] S. Brauksiepe et al ., Nucl . Phys . A 376, 397(1996)
[4] H.-H. Adam, A . Khoukaz, N . Lang, T . Lister, C.Quentmeier, R . Santo and W . Verhoeven, Deu-terium Recuperation for COSY Cluster Torgets,contribution to this report, p .52.
* Institut für Kernphysik, Universität Münster,
20
Luminasity Determination at ANKE with the Speetatar Deteetor
S. Barsovid I . Lehmann, S . Merzliakov2, S . Mildrtichyants l , A. Mussgiller, D. Protic and R. Schleichert
During the ANKE beam time in September, 1999 theprototype of the silicon detector system for the detec-tion of Iow energy spectator protons has been testedwith the deuterium duster target [1] at beam en-ergy of 2 GeV . The telescope-like set-up consisted of3 layers: a 18pm surface-barrier silicon detector andtwo silicon-strip deteetors of 300pm and 5 mm thick-ness were placed inside the vacuum chamber . Parti-des emitted from the target in the polar angle rangeof 77°-110° were detected . With a finite length of thetarget of 15 mm along the beam direction, differentkind of particles emitted in forward and backwarddirections were clearly separated by the strip detec-
tors . The good separation of protons and deuteronswas achieved in AE/E correlation spectra of these
detectorsas well . In the forward direction both, pro-tons and deuterons, were observed (Fig . 1) but inbackward direction only protons were detected . So,the selection of deuterons yields immediately the pd
elastic-scattering process which can be used for theluminosity determination.
0
la
15
20
25
energy [MeV]
Figure
distribution in the strip detectors . Cal-culated dependences are shown by curves.
The energy-position correlation of deuterons (Fig . 2)
is actually related to the energy-angle dependence ofthe elastic scattering: gardel.es of a certain energy are
emitted from the target edge at a certain angle . Po-
sitions where such deuterons are expected to be de-tected in the 5 mrn thick detector are shown by lines.The calculated image of a sharp target edge takinginto account the influence of multiple scattering inthe 300pm detector is presented by the solid curve.Some shift (1-1 .5mm) seems to be due to the dis-placement of either the target or the detector alongthe beam direction . Nevertheless, the shape of theupper border of the experimental distribution is ina good agreement with the expected one with veryfew entries outside this range . The negligible hacke
ground of deuterons coming not from the target has
also been seen . lt cm be identified by the coordinatesof deuterons in the two planes of the silicon strip de-tectors .
0
2
4
6
o
posltion [mm]
Figure
The distribution of deuterons with the total
energy Ed along the 5 mm thick strip detector.
The luminosity was determined by the expression:
L=Yd . ki DT (At .)'
where Yd is the measured yield of deuterons with en-
ergies 16-18MeV. This energy range was Chosen inorder to minimize the uncertainties due to the mul-tiple scattering, the inefficiency of detectors and inorder to simplify the calenlotion of the acceptance.
= 2.5 is the correction factor due to the only par-tially seen target length (Due to the space limitationof the actual ANKE target ehamber, the target cannot be fully seen by this luminosity monitor).DT and Zlt are the deal time of the date acquisitionsystem and the duration of the date taking, respec-tively, obtained from the ANKE system scalers.fAn
1 .38 . 10-29 cm 2 is the pd elastic erosssection for the selected deuteron energy range . The
value of the cross section was taken from [2].Protons 16) 29RUN bunrh DT dt, s Yd 2 .,
1849 5 .5 - 10 2.707 3493 695 1 .0(3)
1853 5 .5 . 109 2 .278 10294 2300 0.9(2)
1856 9 .5 . 109 2 .929 2080 650 1 .7(4)
1857 9 .5 . 10 9 12 .39 2719 200 1 .7(4)
References:
[ 1] H. H . Adam et ah, IKP/COSY Annual Report1998, FZ-Juelich, 25 (1998) and contribution tothis report, p . 20.
[2] J. Bystricky et ah, in "Numerical Dato andFunctional Relationships in Science and Tech-nology" , v . 9, Springer-Verlag, 1980.
PNPI, Gatchina, Russia ; 2 JINR, Dubna, Russia.
8
4
25
20
°-- 15
0'3
o
21
Deteam. Tests at the R;ifilde -Aecel.erotor in Cologne for the Spectator Idenfilierstitan at theANKE-experirnent
S. Barsovi, A. Dewald2 , L Lehmann, Sehleiehert and L. Steinert2
One of the physics goals of the ANKE-spectrometerare studies of elementary reaetions on an effectiveneutron taxget . By identifying the low energetic spec-tator protons from the deuterium duster target, thereaetions on the neutron can be
ed..The telescope-like structure of several layersof silicon-strip deteetors provides the AE/E-identification of protons and deuterons over a largedynamie range, as well as track information for thesepoftidos. To do this tracking and identification inthe projeded energy range, a very thin first layer aswell as thick position sensitive detectors axe needed.These are non-standard detectors and a good under-standing of their behavior is erueial for our applicaation.The Tandem-Accelerator at the University ofCologne can provide a proton beam from 2-20 MeVwhich covers the energy region of interest for thespectator protons. To get a well defined beam athighly reduced intensity we installed a collimator-structure (s„ fig . 1).
Figure The experimental set-up at the Tandem.
Into this oollimated beam we placed a 3mm thickmierosstrip detector (see right side in fig. 1), whichcould be shifted and indined with respect to the pro-ton beam. Independently we could shift a suxfacebarrier deteetor in front of the position sensitive de-tector, and establiste by this a simular setup as in theANKE setup.Fig. 2 shows the bearn energy resolution in a 300 timthick surfacesbarrier detector, which could be repro-duced for all energies from 2 MeV up to 18 MeV.The calibration of all detectors by an ehealibrationtaldng into account pulse hight defegt corrections forenergy-lose es in the dead layer(s) a.nd for nonionizing
contributions in the active layer [1] [2] and experimen-tal results [3] have been compared with the protonbeam-energy. The calibration shows to be reliable onthe per milk level.The signal to noise ratio in the ferst 18 pm thinsurface-barrier detector layer has laeen earefully eval-uated . With the use of a special preamplifier thishigh capaeity detector will provide the ferst layer forthe spectator proton identifi cation . In any case smallarea pads are desireable to improve the energy reso-lution.In addition angular straggling, which limits ourtracking resolution also for a projected vertex de-tector, has been studied . To cover the large energyrange in our thick detector, the dynamic range of theelectronics had to be earefally considered . This is es-peeially true for the r - . ' out with a resistor ehain.lt could be concluded, that a single-strip r- . s out isneeded. Another task, which could be evaluated, haslaeen the dependence of the energy deposit on theangle of the incident poftide.The sketched outeome of this t t beam time shows,that the use of the Tandem-Accelerator at Cola : eyielded a good check of detector proparties . We hopethat these results can contribute even further to thedevelopment of the "Spectator Setup" at ANKE asthey already did in the last beam time.References:
[1] J . Lindhard, V. Nie - s Phys . Lett . 5 (1962) 209.
[2] F. M. Ipavich et al NIM 154 (1977) 291.
[3] W. N. Lemtard et al NIM A248 (1986) 454.
PNPI, Gatehina, Russia2 IKP, University of Cologne
.s
s.s
6.0
enengy [W]
Figure 2 : Tandem beamsenergy resolution
22
Monte-Carlo Simulations for the ANKE Spectrometer
1 . Zychora
The Monte Carlo code GEANT [1] is used tosimulate experiments with the ANKE spectrome-ter. The program is located under the follow-ing address : http :/likpd15 .ikp .kfa-juelich .de :8085/doc/Anke .html . Three files : fieldamaps .tar .gz, in-put .intuplesroc .tar.gz and izargeant .tar.gz are nec-essary for this purpose . The main program mustbe adjusted to the particular problem to be ana-lyzed by the user . Information about input filesfor the ANKE-GEANT code can be found in man-uals available in the iza_geant .tar .gz file . A fileiza-momentum .tar, located under the address givenabove, provides programs for the momentum recon-struction based on the information from multiwireproportional chambers (MWPC).
One of the major parts of the ANKE-GEANTprogram is the geometry package which has two mainfunctions : (1) define, during the initialisation of theprogram, the geometry through which the particleswill be tracked, (2) communicate, during the eventprocessing phase, to the tracking routines the infor-mation for the transport of the particles in the ge-ometry which has been defined.
The ANKE-GEANT geometry package preciselydescribes the full spectrometer : magnets, vacuumchambers, target chambers, detector systems etc.The real setup is divided into parts easily convertedinto shapes supplied by GEANT . Preparation of thedescription of the ANKE geometry for the Monte-Carlo code was a time consuming task which hasstarted from measurements of dimensions and po-sitions of all ANKE elements . Necessary data arealready placed in the ANKE WWW page and in thenear future will be available from a data base . Mea-sured dimensions and positions of all elements of theANKE setup are then used to calculate shape pa-rameters and positions of volumes ahcarding to theGEANT convention . For the moment these con-versions are done in the main part of the ANKE-GEANTprogram (written in FORTRAN).
All physical phenomena (pair production, Comp-ton scattering, photoelectric effect, Rayleigh scat-tering, Bremsstrahlung, hadronic process, annihi-lation, 5-rays, muon-nuclear interaction, photo fis-sion, decay in flight, energy loss, multiple scattering,Cerenkov photon generation, Cerenkov light absorp-tion, synchrotron radiation generation, different en-ergy fluctuation models) can be switched on or offby the user . Values of parameters controlling theseprocesses must be chosen by the user.
For the description of the magnetic field in thespace occupied by the ANKE facility the measuredfield maps are used in combination with three dimen-sional field calculations made with the MAFIA code[2] . The tracking calculations were checked by com-parison with the floating wire measurements [3] andare in good agreement with the data .
Full information about events can be obtained Bi-
ther from special flies described in manuals or fromGEANT original output fites, prepared by callingcorresponding procedures [1] . One event consists ofseveral tracks and more than one particle can appearin it . Typical parameters of the particle track, liketime of flight, energy loss and path length for eachdetector, are stored . These data can be written inthe same format as used for measured data . So, thesame data analysis program may be used for experi-mental and simulated data.
Simple response functions for scintillators areimplemented in the ANKE-GEANT program andplaced in a ntuple-like file.
Monte-Carlo simulations are very useful to de-termine detector acceptances, estimate backgroundand to understand measured particle spectra. Thesecalculations are also necessary for identification ofparticles and calculations of their energy losses . TheMonte Carlo simulations are the only method to re-construct the momenta of ejectiles, from measuredhits in MWPC's for the two body calibration reac-tions . Calculated and measured parameters are usedto verify positions of setup elements, or even to findcorrect values (e .g . by comparing the simulated andexperimental hit distributions in MWPC's).
References:
[1] GEANT3 Manual, CERN Program LibraryLong Writeup W 5013 (October 1994)
[2] MAFIA, The MAFIA Collaboration
[3] S. Barsov et al ., "Dipole Field Characterizationby Floating Wire and Field Map Ray Tracing",Proc. 16th la. Conf . on Magnetic Technology,Ponte Vedra Beach (USA), Sept .26 Oct .2, 1999
aThe Adrzej Soltan Institute for Nuclear Studies,PL-05400 Swierk, Poland
23
Planned measurement of the branching ratio ao
+r1/K+re with ANKE*
M . Büscher, V . Chernyshev a , L.A . Kondratyuk a
The structure of the fightest scalar mesons ao(980)and fo(980) is not understood yet and is a fundamen-tal problem of hadronic physies (see [1]) . In partic-ular, the branching ratios for their decays into dif-ferent strange and non-strange mesons is basicallyunknown. So far, the charged components of theao(980) meson were mainly studied in the Irr+ andi7rr° channels [2] . The data from only one experiment[3] where ao decay into KK was observed after pp an-nihilations are used for the analysis by the ParticleData Group [4].lt has been proposed [5] to measure at ANKE thereaction pp -4 da'01i at energies between threshold(T = 2.49 GeV) and the maximum COSY energyat around 2 .6 GeV . The original proposal foresees aprecision measurement of the an -mass distributionin the K+-g0 decay channel at various beam ener-gies. The a'c4)- mass will be reconstructed from themeasured momentum of the outgoing deuterons . Theanalysis of the mass distribution requires data withhigh statistics, thus, for the measurements a highdensity frozen pellet target [6] is neccessary whichwill supply luminosities of up to -- 1032 cm-2s +1 .In an early stage of the investigations, using the ex-isting cluster jet target [7] with lower density, it isplanned to measure at maximum COSY energy thebranching ratio ac+)" ir+ r7/K+K0 by a simultaneouscoincidence measurement of dir + and dK+ pairs, re-spectively . Figure 1 shows the result of GEANT sim-ulations an ejectile trajectories which were performedto estimate counting rates and to develop methodsfor background suppression.
D2
Figure 1 : GEANT simulations for the trajecto-ries of the charged ejectiles from the reactionsp(2 .62 GeV)p -4 da iof' dK+lt (left) and -+ dir +ii(right) . The field of dipole magnet D2 is indicatedas a rectangular box ; the measurements will be per-formed at a field strength of B = 1 .57 T in D2.
Figure 2 shows reconstructed missing mass distribu-tions for the two exit channels of interest as cal-culated from the simulated GEANT events . lt canbe seen that with the mass resolution achievableat ANKE (Zlirn < 10 MeV/c 2 ) the a"j- meson canclearly be identified . The count rate estimates givenin Fig.2 were calculated assuming a luminosity ofL ---g 2 - 1033 cm's+l and include effects Ilke decayin flight, geometrical acceptance of D2 as well as the
deteetion efficiency in the different counters . lt hasbeen assumed that above the K + K threshold the
decays with equal probabilities into in) and KK.The cross section estimate u tot 100 nb is takenfrom [1] . lt can be seen that within a beam time ofapproximately two weeks suffizient statistics can beobtained to draw conclusions about the branchingratio into the two decay channels.
-9' 0.6Inn
mK
0.6
0.8missing mass (d), GeWe2
Figure 2 : Reconstructed missing mass distributionsfor the two at-decay channels as well as for one pos-sible background ehannel with ir+ production via thep meson.
Figure 2 also shows the mass distribution for oneof the possible background channels (with the for-mation of an intermediate p + meson) where ais detected in coincidence with a deuteron . Clearly,this background can be suppressed at ANKE due tothe high mass resolution . Our simulation calculationsshowed that this is also the case for other backgroundchannels, e .g ., from the reaction pp pir +X wherethe proton is misidentified as a deuteron in the for-ward counters . For the case of dK + detection it hasalready been shown in [5] that the background canbe sufficiently reduced.ReTerences:
V.Yu . Grishina et al ., contr . to this report, p .25.
S . Tiege et ah, Phys .Rev . D 59 (1998).
L .de Billy et al ., Nucl .Phys . B 176 (1980) 1.
C.Caso et al . (Particle Data Group), Eur.Phys .J . C 3 (1998) 1.
V.Tchernyshev et a1 ., COSY proposal No .55"Study of at mesons at ANKE";LA.Kondratyuk et al ., Preprint ITEP 18-97,Moscow (1997).
W . Borgs et ah, contr . to this report, p .35.
H.-H. Adam et al ., contr . to this report, p .20.
'Institute of Theoretical and Experimental Physics,B. Cheremushkinskaya 25, 117259 Moscow, Russia* Work partially supported by DFG and RFFI.
1 .5
) daö --- mir-h
-°
4
4st° .
%ea°
20 h -i rtteP
PP
[5]
[6]
[ 7 ]
24
Production of 4-mesons in the reaction pp
near threshold*
V.Yu. Grishinaa , L .A . Kondratyuk b , M . Büscher, E.L. Bratkovskayac , and W . Cassing'
The scalar meson sector plays a very important rolein the physics of hadrons . Nevertheless, the structureof the fightest scalar mesons ao(980) and f0(980) isnot understood yet and is one of the most impor-tant topics of hadronic physics (see e .g . [1, 2, 3] andreferences therein) . They can be either "Unitarizedqi:i states", or "Four-quark cryptoexotic states", orKK molecules or vacuum scalars (Gribov's minions).Nowadays some preference is given to UnitarizedQuark-Model (UQM) states . However other optionscannot be mied out completely. Moreover, there isa strong mixing between the uncharged 4(980) andthe fo(980) due to coupling to KK intermediate states[2] . Therefore, it is important to study the chargedcomponents of ao(980) which are not mixed withthe f0 (980) and preserve their original quark content.Good conditions to study the a -oli (980)-meson in the
-oreactions pp ei+ d ao+ -+ d K+ K , pp -+ d
d 7r + 1'7
can be realized at ANKE (see [4, 5]).The missing mass spectrum in the reaction pp --+d X+ for deuterons produced around 0° in the Iah-oratory and incident momenta of 3 .8, 4 .5 and 6 .3GeV/c has been measured previously at LawrenceRadiation Laboratory (Berkeley) [6] . lt is interestingthat apart from the peaks corresponding to rr andp production, there is a dinstinctive structure in themissing mass spectrum at 0 .95 GeV 2/c2 which wasidentified with a0 production . The corresponding dif-ferential cross section for the forward au productionis shown by the open circles in Fig .l.In order to estimate the cross section of the reactionpp -+ d ao+ at lower momenta which are available atCOSY we used two different approaches:i) the quark-gluon string model (QGSM) withthe properly antisymmetrized Reggeon amplitude(AR (s,t) - AR(s, u)) normalized to the LRL dato,at 4.5 GeV/c ; ii) the two-step model described bymeson exchange diagrams where ao couples to twodifferent nucleons through f 1 (1285) and ir-exchanges.The coupling of the f1(1285)-meson to nucleons wastaken from [7].The results of caIculations of the forward differen-tial cross section at differenet gab are presented inFig.l . The solid curve shows the result of the QGSM.Two dashed curves describe the results of TSM cal-culations using different values of the pion cut-offparameter, A = 0 .8 and 1 .3 GeV. The predictions ofthe two models are consistent and give for the inte-grated P-wave cross section of ao-production a valueof about 0 .16 (0 .12) with an uncertainty of about30% at Tlab= 2 .62 (2.6) GeV. Consequently, it willbe feasable to detect the reactions pp
d ao+ -+d K+e and pp -4 d a -d- -+ d 7r+ u at ANKE (see[4, 5]) .
Figure 1 : Forward differential cross section of thereaction pp -4- daä as a function of (na), - 3 .29)GeV/c . The empty circles are the experimental dato,from Ref .[6] . The solid curve describes the result ofQGSM . The two dashed curves are calculated withinthe TSM with different values for the pion cut-off pa-rameter : A, = 0 .8(lower curve) and 1 .3 (upper curve)GeV.
References:
F.E. Close et al ., Phys .Lett . B 319 (1993) 291.
G . Janssen et al ., Phys .Rev . D 52 (1995) 2690.
S. Narison, "Gluonia-Scalar Mesons-Hybridsfrom QCD Spectral Surn Rules", Review talk atHADRON-99, Aug . 24-28, 1999, Beijing, China.
[4] V . Tchernyshev et al ., COSY proposal No .55,"Study of an mesons at ANKE" ;L .A.Kondratyuk et al ., Preprint ITEP 18-97,
Moscow (1997).
M . Büscher et al ., contr . to this report, p .24.
M .A. Abolins et al . Phys.Rev .Lett 25 (1970)469.
M . Kirchbach et al ., Nucl .Phys . B 176 (1980)1.
'Institute for Nuclear Research, 60th October An-niversary Prospect 7A, 117312 Moscow, Russia°Institute of Theoretical and Experimental Physics,B . Cheremushkinskaya 25, 117259 Moscow, Russia'Institut für Theoretische Physik, UniversitätGiessen, D-35392 Giessen, Germany
Supported by DPG and RFFI.
[ 1 ]
[2]
[3]
[ 5]
[6]
[7 ]
25
Possibility to search for wNsresonanees in the reaetion pp e+ wpX at ANKE*
M . Büscher, V .Yu . Grishina a , V. Hejny, L .A . Kondratyukb , and H . Ströher
The couplings of nucleon resonances to channels in-volving a vector meson (p or w) and a nucleon isan important issue of hadronic physics . The quarkmodel predicts a series of resonances which have largerelative probabilities to decay into pN and/or wN fi-nal states (see, e .g ., [1, 2]) . Experimentally almost adozen of N*'s are known which decay into pN [3],but up to now no nucleon resonance which decaysinto the wN final state has been observed. There-fore, it is a great challenge to find experimentallysuch a decay. There is one experiment in Progressat TJNAF [4] where it is planned to search for aN*(1955)(5/2)-f "missing" resonance, predicted tohave strong 7N and wN couplings and an almostvanishing irN coupling [1, 2].Here we want to stress another good candi-date to Look for an wN decay is the resonanceN*(1720)(3/2) + . According to [3] its branching frac-tions for irN and pN decays are equal to (0 .1-0 .2)and (0.7-0 .85), respectively . The predicted branch-ing fraction for the wN channel is comparable withthat for irN [1] . To estimate the cross section ofthe reaction pp -+ pN+ (1720) it is useful to com-pare it with the cross section of the similar reactionpp -+ pd+ (1232) . The ratio of the cross sections in-duced by ir 0 exchange can be written as follows forthe saure c .m . energy release Q:
ir (PP-4PN *)
(ein -m 7,2 )21` N i --ipir 0
0hr (PP
PA )
(trnN:n
-ip7 0
where t rnin is the minimal momentuni squared . Wefind R, ,hi (1 .5-3) . lo-2 which would correspond too-,r (pp pN*) hri. (30 - 60)pb . The contribution of p
exchange might lead to an even larger cross sectionbecause of a larger F(N*
Np) branching fraction.Therefore we can use for an estimate
o''(PP pN*) = ir pp -4 pN*) + crp(pp pN*(60 - 120) pb
( 2 )
at Q = 0.15 - 0 .25 GeV. Taking the branching frac-tion BR(N*(1720) wN) hr. 0 .1 we find that thecross section of the resonance mechanism of omegaproduction in the reaction pp -9> N*+ (1720) -+ w ppwill be about (6-12)pb . The total cross section ofthe reaction u(pp -+ ppw) at COSY energies can beestimated using the parametrization of Fäldt andWilkin [5, 6] . At Q = 150 - 250 MeV we haveo-tot (pp -+ ppw) Pe (12 - 20)pb. Therefore, the crosssection of resonance production in the wN channelis expected to be an essential part (about one half)of o-tot (pp pp.)) . This means that the possibilityto detect the wN decay of the N*+ (1720) in the re-action pp -ei ppw at COSY is quite promising.The experiment at ANKE can consist of the follow-ing steps: i) Measurement of the missing mass dis-tribution do-/dM of the wX system, produced in the
reaction pp -+ pfastw(ir0 7)X at different plan from2 .7 to 3 .4 GeV/c, detecting a final fast forward pro-ton in the ANKE spectrometer and triggering on wthrough its decay by a photon detector. Thenthe reaction pp -+ pf,„stw(ir07)pslo, can be identifiedand the resonance contribution corresponding to thereaction pp -+ pfastN+ (1720)slow can be separatedfrom the background ; ii)Confirmation of the spin-parity of the produced resonance analyzing the wpangular distribution and determining the elementsof the resonance density matrix.The reasons why it is important to use the pho-ton detector in this case are the following . De-tecting only two protons in the reaction pp -+pfastwpsi ,,v, at ANKE one could reach a moderateresolution in missing mass of about 5 - 10 MeV.In this case the selection of the reaction pppfastN+ (1720)slo w pwp will be quite difficult be-cause of rather large background from the reactionpp --+ pfäst N+ (1720)s i ow -+ ppp . (Note that the reso-nance production of p meson is expected to be by anorder of magnitude more intensive) . On the otherhand no large background is expected in the ir'-ychannel for invariant mass near 0 .78 GeV. For ex-ample, there are experimental data on the inclusivereaction pXe-+ 37X at plab < 0.9 GeV/c with theresolution in invariant mass of 37 system of about40 MeV [7] . In the distribution of the events in ther0-y invariant mass there is a background from thereaction pXe-+ 2ir 0 X but in the w-mass region0.6-0 .8 GeV it is smaller than the w Signal . As in ourcase the main source of background is related to p-meson production and because p does not decay into27r° we expect smaller background in the r 0 -y chan-nel . We can conclude that there are good chancesto find wN decay of the N*+ (1720) in the reactionpp -> ppw at COSY.
References:
[1] R. Koniuk, Nucl .Phys .B 195 (1982) 452.
[2] N.Isgur, G.Karl, Phys.Rev .D 19 (1979) 2653.
[3] Particle Data Group, Eur .Phys .J . C 3 (1998
[4] V.Burkert et al ., CEBAF Experiment 91-024.
[5] Fäldt, G., and Wilkin, C ., Phys .Lett .B 382,(1996) 209.
[6] F.Hibou et al ., reucl-ex/9903003.
[7] V . Barmin et al ., Yad.Fiz .59 (1996) 1886.
'Institute for Nuclear Research, 60th October An-niversary Prospect 7A, 117312 Moscow, Russiab lnstitute of Theoretical and Experimental Physics,B. Cheremushkinskaya 25, 117259 Moscow, Russia* Supported by DFG and REH.
26
production in p + p interactions near threshold
H. Müller', V . Hejny
Usually i production near threshold is assumed toproceed via the formation pp -4 pN*(1535) and sub-sequent decay N* (1535) -4 pn of the N*(1535) res-onance (see e .g. [1]) . On the other hand, a nonres-onant production mechanism pp --si ppri cannot beexcluded . For the understanding of n production itis important to obtain experimental information onthese two basic mechanisms, especially of their rela-tive contributions to the total cross section . In case ofresonant production one expects to see a peak in theinvariant mass distribution of p + n, while the non-resonant production should yield a fiat distribution.Since the width of the N*(1535) resonance itself israther large it is necessary to measure at high enoughenergies in order to cover a region of the invariantmass which is sufficient to distinguish between thetwo mechanisms . This requires a measurent of theejectiles with high acceptance . Thus the planned In-stallation of a photon detector at the spectrometerANKE covering a wide angular region is a necessaryprerequisite for measuring the produced mesonswith high efficiency via the decay into two photons.The following discussion of a possible experimentis based on calenlotions carried out with theROC model [2] . This is an empirical approach sam-pling complete events . Particle production proceedsvia the creation of quark pairs and/or via the ex-citation of resonances. Thus resonant and nonreso-nant production is included and the correspondingeffects can be studied . In the following it is assumedthat protons can be detected in the angular region0° 0 < 10° and photons in 25° 0 < 120°.The momentum resolution is simulated by addingto each calculated momentum an isotropically dis-tributed vector the modulo of which is sampled froma Gaussian having a width of (7=4% for photons and1 .5% for protons .
p(2 .5GeV)+p
y+y+p+X
Figure 1 : Invariant mass spectrum of two photons(left hand side) and missing mass speetrum of a pro-ton with two photons having an invariant mass inthe region around the peak (right hand side) . Thevertical Bars indicate the regions used for selectingthe reaction pp -ei> ppn.
In Fig . 1 it is demonstrated how the reaction of inter-est can be selected. The invariant mass spectrum oftwo photons shows two peaks originating from ir 0 and
ri decay . With a window set on the peak the missingmass spectrum of Typ exhibits a strong peak aroundthe proton mass . Thus by setting a second windowon that peak the final state consisting of two protonsand an n meson can be well separated by detectingone proton and two photons.
p(2 .5GeV)+p
p+p+in0 .2
0.15COibE 0.1
iD o.o6b0
.4
1 .6
1 .8
2
1 .6
1 .8
2
inv . mass M im,
miss . mass AA,
Figure Invariant mass spectrum of p + i (left handside) and missing Mass spectrum of one p (right handside) from the reaction pp ppn . The dashed his-tograms are build from events having an intermedi-ate N*(1535) resonance, while the dotted histogramsare from the nonresonant events.
The two protons in the considered final state are in-distinguishable . In case of a resonant production eachof them can arise from the decay of the N*(1535).So one may look for the presence of the N*(1535)either in the invariant mass spectrum of p + or inthe missing mass spectrum of the p . The result ofFig. 2 seems to contradict this expectation . Whilethe invariant mass spectra are fiat both for resonantand nonresonant events the expected signal from theN*(1535) decay is clearly seen in the missing massspectrum. The reason for this behavior lies in thesmall forward cone in which the protons are mea-sured. Protons from the decay of the N*(1535) on theaverage get an additional sideward kick and thereforethey are detected with a smaller probability than thenonresonant protons . Thus we see the expected effeetin the missing mass spectrum of the measured pref-erentially nonresonant proton.lt should be mentioned that effects Ilke interferencesor final state interactions are not considered here.For energies dose to threshold (excess energyQCM 16 MeV and 37 MeV, respectively) thesetopics have been discussed recently [3] . The pro-posed measurement should give more insight intothe production proeesses in the whole N*(1535)resonance region.
Referenhes
[1] T. Vetter et al ., Phys . Lett . B 263, 153 (1991)
[2] H . Müller . Z . Phys. A 355, 223 (1996)
[3] H . Calen et al., Phys. Lett . B 458, 190 (1999)
1 Forschungszentrum Rossendorf, Institut für Kern-und Hadronenphysik, 01474 Dresden, Germany
27
Negatively charged partic e detection atH.R.Koch, R. E; , M. Hennebach
The accepted ANKE experiments "Subthreshold K"production" and "(l:i production in pn eh. dM reactions"
require the measurement of K mesons . A detectorsystem similar to that used for the measurement ofpositively charged ejectiles (the "side detector") is imderconstruction . lt will be placed partly inside the Iow fieldhole (magnetic field 0 to s--200 mT) of the C-shaped D2magnet, partly outside the D2 magnet (Fig . 1) . At themaximurn field of D2 (1 .6 T) negatively charged ejectilescan be measured in the momentum range from ,---120 to
1 . 4 MeV/c. For c~a production in the p + nucleonreaction at threshold the momenta range from 403 to795 MeV/c. If mesons or K- Tafts are produced in p+ nucleus reutions the momenta of K- ejectiles varyfrom ,i--200 to ia- 1
MeV/c [1] . The horizontal andvertical angular acceptances are roughly:
,-.±-12°;8° at 200 MeV/c and ahor=-2 to 12°, airngs-eh.5 0 at
1000 MeV/c.The negative partiele detector system consists of
two MVVPCs for precise track and momentumdetermination and of "statt"- and "stop"- scintillators forTOF and AE measurement used for particle identification.In the K--ex perirnents the expected major backgroundcomponents are negative pions from the target andprotons scattered from the magnet yoke, from the vacuumehamber and from the deteetors . lhis background exeedsthe K- intensity by some orders of rnagnitude. Assumingthat the same precision of tirning measurements will beachieved as on the positive partkle side of ANKE((Ja-240ns), the measured flight times allow reliable kaon-pion diserimination up to a--500 MeV/c (ST > 4z) . Forhigher momenta up to 1000 MeV/c flight time differencesreduce to 2a of the timing resolution, in spite of theTonger flightpaths to the "stop" scintillator group II . Thisdifference is not sufficient for separation if the K»intensity amounts to less timt' 1% of the pion background.On the positive partiele side background reduction isachieved by the measurement of AE in the focal sutface ofthe D2 magnet after degradation of the makle energies.In the high momentum region of negative ejectiles theenergies are too large and the focal surface is far off,
g the use of degraders impractical . Thus AEinf orrnation is less conclusive . For the detection of veryweak K+ intensities background suppression was mostefficiently achieved through the detection of delayedmuons from the decay of stopped K+-mesons . Thismethod earmot be applied for
identification.mesons at lest are captured in kaonic atoms, whoseUniahne is too short to produce signals of measureabledelay.
For these reasons relatively sophistieated Cherenkovdeteetors are being built for the negative-particle side.They consist of bars of Weite which are slightly trenn Thecalenlotion of the particle trajactories shows that outsidethe high field region of D2, partkles criginating from thetarget seem to come from a narrow line shaped region,loeated in the midplane of the D2 gap . If the deteetor barsare bent in a way, that the front surfaces focus to this"virtual target", the verdeal component (measured in the
vertical plane through the trajectory) of the angle with thedeteetor front surface varies only by less than 1° along thedeteetor . For a straight detector element this variationwould amount to t-r-10°, depending on the momentumregion . Therefore properly bent bars of Weite can be usedas differential Cherenkov deteetors . The appropiate radiusof curvattre is s--2 .4m. The Cherenkov light from pionswill be totally reflected at the detector side faces andpropagate to the PMTs at the end faces . The Cherenkovcone of kaons has a smaller opening angle and the lightwill leave the deteetor at its side faces. Simulationcalenlotions were carried out in which realisticmomentum and angular distributions of the pardeletrajeetories were taken into account . The production aridpropagation of Cherenkov Iight in the deteetors wascalculated . The results show that die to the spread of thehorizontal components of the angles of partiele incidence,also K mesons may produce Cherenkov light whichreaches the PlVlTs . Ilowever the intensity of the de ted"Kaon Light" amounts to less than 3% of the intensity ofthe "pion light" . This number does not change drastieallywhen statistical fluctuations of the light production andpropagation process are taken into account . Botte,calenlotions and Lest measurements have shown that evenfor deteetors of a thicImess of only 2 cm, pion-kaonseparation for partkles coming from the target can beachieved [2].
Fig .l : The ANKE detection system for negatively chargedparikies
References:[1] A. Sibirtsev, M. Büschen H.Müller, Ch. Selmeidereit,
Z. Phys. A 351, 333 (1995)[2] M. Hennebach, Untersuchungen zum Einsatz von
Cerenkovzählern mit Totalreflektion für dieTeilchenidentifikation an ANKE, Diploma thesisUniv . Köln, Dec . 99
et ei.imnumustuammwA
11111111O1M2MT.Tre211W4III1Med502r40Y2:..rIn1113111111111111M1MW1I1IMIlrIl/41M/41älPirdzerderig
.j11111111111»n n .
28
First Measurements With The ANKE Forward öerenkov HodoscopeG . Borchert, B . Chiladze 2 , R. Eßer 1 , M. Hennebach, A . Kacharava''3 , R. Koch, V. Komarov 3 . A. Kulikov 3 ,
G. Macharashvili 2,3 . M. Nioradze 2 . A . Petrus '
The forward Cerenkov Hodoscope (CH) has beendesigned for ANKE mainly to seperate deuteronsfrom protons with momenta between 1 and2.5 GeV Cerenkov counters using total inter-nal reflection have been proposed for ANKE first in1994 [1] . A detailed deseription is given in [2].
The CH consists of two identieal sets of countersmode of UV transparent Plexiglas GS 218 . The rect-angular active area of each module is adapted to thesolid angle covered by the forward scintillation ho-doscope (FH, [3] ) which itself is optimized for theaperture of the spectrometer dipole D2 . For read-out 2 -inch photomultiplier tubes (PMT) XP 2020are used. Eight modules below and 8 above the midplane of ANKE have been installed. For each modulethe inclination angle with respect to the vertical di-rection of each module can be varied in a wide range.The thickness of the not inclined radiator along theparticle path is 5 cm, the width is 8 cm.
The first test of the CH has been performed using aproton beam of approximately 2 GeV hitting a deu-terium duster target in September 99 . The FH lo-cated very dose in front of the CH was used as a trig-ger . In the left figure a typical amplitude spectrum ofa Cerenkov counter is presented . The events withoutany signal are shown in channel #0 to visualize theratio of events with and without a Cerenkov signal.
While the amplitudes of the Cerenkov signals do notdepend on the particle hit position, the timing ofthe Cerenkov signals is strongly correlated with thevertical coordinate y. The START for all TDCs isgiven by a trigger using meantimer signals from theFH. Thus START is coordinate independent and thetime spectrum reflects the propagation time of Ce-renkov light from the point of incidence to the PMT.By looking at events with the same y it is possi-ble to estimate the time resolution ( FWHM ) of theCerenkov counters as approximately 420 ps . The co-ordinate resolution of the FH is taken into account .
For the studied momentum range deuterons shouldnot produce any Cerenkov signal . Nevertheless,rauch more zero amplitude events are detected thanthe expected number of deuterons due to simulationcaldulotions. These are probably Iow energy parti-des scattered in the magnet poles of D2 or in theexit fiange of the vacuum ehamber of D2 . This hy-pothesis is proven by the correlation spectra : In thecentral figure the energy loss AE 1 in the first planeof the FH is plotted versus AE2 in the second planefor all particles . For fast, minimum ionizing par-ticles from the target they should be uncorrelated.Nevertheless, a correlation is observed as an eventcumulation along the diagonal . In the right figurethe same plot is presented only for events without aCerenkov signal . Here the correlation is evident andis explained by the strong dependence of the energyloss on the momentum for Iow energy particles . Notethat this also includes fast deuterons from the tar-get which do not create a Cerenkov signal . They areshadowed by the background but can be emphasizedby backward tracking.
This work is supported by INTAS - Georgia GrantNo.97-500.
References[1] N. Amaglobeli et al . : New Type Of Cerenkov
Counter Of Total Internal Reflection, PreprintHEPI TSU 08 -94. Tbilisi ( 1994 )
[2] A. Kacharava et al . : Beam Test Of CerenkovCounter Prototype For ZDF Setup, NIM A 376(1996) 356
[3] G. Borchert et al . : ANKE Forward Ho-doscope : First Beam Measurements, IKP 1998Ann. Rep . FZ- Jülich ( 1999 ), p . 20
1 IKP, Universität zu Köln, Germany2 HEPI TSU, Tbilisi, Georgia3 JINR, Dubna, Russia
3000
2000
1 000
0
Cerenkov Amplitude
Fwd .DE .l vs Fwei .DE,2
Fwd .DE.1 vs Fwd .DE .2 (-Cer
29
Readout for front-end Chips of Silicon Strip Deteetors
A. Mussgiller, M. Drochner, R . Schleichert and P. Wüstner
A possible readout system for douhlessided Si-stripdetectors with front-end Chips [1] based on a mim-mercially available solution in VME has been stud-ied in detail . The setup consists of two single slotwide VME units, a ADC V550 [2] and a sequencerV551b [3] . The V550 ADC ho es two seperate ADCchannels with a resolution of 10bit arid is eapableof storing the dato for a maodmum number of 2016deteetor strips per channel . Pedestal and thresholdregisters are provided for every detector strip. TheV551b sequemer is the control unit of the setup . ltcontrols the ADCs as well as the front-end Chips al-lowing a reasonable amount of flexibility to justtiming between the front-end chips and the ADCs.The conversion time is specified to be 200ns which
70
10
50
los
150
200
300
number of used deteetor ehanneis
Figure conversion time as function of the number of
detector strips
corresponds a maocimum conversion rate of 5 MHz.B the plain conversion time for the num,ber ofused detector strips a common offset at least 750nshas to be added due to a control sequence for thefront-end chips before every readout . Fig. 1 showsthe total conversion time as a function of the numberof used detector channels for a minimum offset and aconversion time of 240 ns for each deteetor ehannel.The conversion time can be calculated according to
t nstrips tconversion + toffsetFor overall performance and deadstime measure-ments a standalone DAQ system has been setup . Infig . 2 the total time for a sequence of 16 bit readoperations is ploted, showing the plain PCI-toVMEperformance . According to the figure the time for anumber of operations on the VME bus can be caleu-lated by the equation:
t noperations ° 8 .0 ps + 29.7 ms
The readout routine has been programmed to loopover the number of used V550 ADC modulas whilefor ADC channel the number of above t , holddata-words arid the actual dato was read . The overalltime for one amepted tri er is thus the sum of theconversion and the r out time . Fig. 3 shows thed e of the system as a function of the num-ber of used ADC urüts . During the measurements
5
10
15
20tumber of 16bii read operations
Figure
-out time as a function of reut operations
Figure 3 : deachtime as a function of the number of usedV550 ADCs
threshold valu were set to a value where dato weresuppressed and the ADC conversion time was set to240 . lt is obvious that the de -time of such sys-tem will be very high even for a small number of de-tector chmmels. For a setup with e.g. 10000 detectorstrips, readout by 20 ADCs, the dead-time would be
ms. Neverthel :.r . the setup will be used for thefixst test deteetors until a faster solution hernrareavailable . There is also the possibility to optimizethe plain PCI-to-VME performance by a faetor of 3and to introduee additional t er-logic in order tore° :e the total number of r seycles per event.
renees:
Integrated Detectors Sa Electronics AS,http:/jwww.ideas .no.
[2] CAEN spa. Technical Information Manual-Mod. V550 (2 Channel C-RAMs), 1 edition,4 1998.
[3] CAEN spa. Teelmical Information ManualsMod. V551b (C-RAMs Sequencer), 1 edition,4 1998 .
32 stripso o 64 strips
128 strips256 strips -'
7
9
10
11number of V550 units
30
Evaluation of front-end Chips for SUkort Strip Deteetors
A . Mussgiller, S . Barsov 1 , S . Merzliakov2 , D . Protic and R. Schleichert
The read-out deetranks of the ANKE silicon stripvertex detector will be placed close to the detectorsinside the COSY vacuurn . For this task specially de-signed front-end amplifiers are available. To fulfill therequirements of a high dynamic range combined witha seif-triggering eapability of the deteetors, a chipcombination produced by the norwegian companyIDE AS [1] has been evaluated . The chip combinationconsists of an amplifier part called VA32HDR anda TA32C [3] trigger Chip . Both chips have 32 inputsand can be used for deteetors with a minimum strippitch of 200 im . Fig. 1 shows the principle scheme ofthe VA/TA Chips.
Figure 1 : Principle scheme of the VA/TA
com-bination
The inputpads are directly bonded to the detector-strips . The output signal of the VA32 preamplifier issplit into a slow and a fast braneh . The slow branch(1 ps shaping time) resides inside the VA32 . Once areadout-cycle is started by asserting a hold signal theenergy information is stored so that the analog datacan be read out channel by channel using the outputmultiplexer and eonverted by an ADC . For triggerpurposes the fast Manch is fed into the TA32 chip(75 ns shaping time) via bond bridges . The outputof the TA fast shaper is compared with a commonthreshold voltage giving the opportumty to ()Maina trigger signal from the An additional shiftregrnter allows to select an individual trigger Pattern.The VA32 can be set into a testsmode, in whieh oneehannel can be selected for electronic tests . In thismode a defined Marge ean be applied to the input ofthe selected preamplifier via the "test pulse" input.The VA32HDR has according to the specificationsa linear range of ±230M1Ps where 1 MIP equals toan input Marge of 3 .6 fC . The total range of energylosses for silicon is thus from 80 keV to 18 MeV . Sincethe in- arid outputs are bipolar, the ehips can alsobe used for double-sided silicon-strip deteetors wherepositive signals are ohtained on the p-side and neg-ative signals on the n-side .
For the evaluation a simple r out system basedon a Windows-PC, a test detector and an interfacehas been used . Goal of the evaluation was to Ire>ify the specifications, espeeially the linear range ofthe VA32HDR and the capabilities of the TA trig-ger Chip . Most of the tests have been done using thetest-pulse input of the VA32.
peaking time
Figure 2: Peakingstime as a funetion of the inputeharge
testpulses of 17 fC and 800 fC
Figure 2 shows the peaking-time as a firnetim of theinput charge for a selected c el . Since the delaybetween a trigger and the assertion of the hold sig-nal is fixed by the external eleetronics the variationof se200 ns leads to a Ioss in energy resolution . For a
2 .2
2
1 .2
1-1600 -1200 -800 -400
0
400 800 1200 1600input charge in fC
C®Vi 140.0
135.0
130.0
1210
120.0
1130
110.0
105.0-10 00
:. 2.0
4 .0
6 .0
OA
10.0
123 lud(mV} 1400 .0
1200 .0
1000 .0
600 .0
peakingtime for 800fC
600 .0
400 .0
0 .0
-200 .0-Iß Oß 20
40
6A
&O
1OD 123 Cl
Figure
Si
peakingdme for 17fC
7
31
hold delay of for instance 1 .2 us the delay is optimalfor charges between 600 fC and 1100 fC. For chargesoutside this range the signal has not yet reached itsmaximum and thus the wrong energy-loss is saxnpled.Fig . 3 shows this behaviour for two different input-charges . For a test-pulse of 17 fC the peakmgstime islonger than for a test-pulse of 800 fC . If the peaking-time is set correctly for charges of 17 fC, signals ob-tained by a Charge of 800 fC are sampled incorrectand vice versa . For negative charges with higher vari-ations (700ns) the loss in energy resolution is evenhigher . In any case it is a systematic effect which eanin principle be corrected in an off-line analysis.Fig . 4 shows the linear range of the VA32HDR . Forpositive charges the specifications are satisfled sincethe linear range is more than a factor 250 accordingto the measurements . For negative charges the lin-ear range is mach smaller . From the tests performedusing the test-pulse option of the VA32HDR, satisfy-ing energy measurements seem possible for positivecharges while for negative charges the linear rangeis limited. One possible option to extend the linearranges for one polarities could be to shift the zeropoint, but this has to be verifled.
signal profite
Figure 4 : Output amplitude as a function of input Charge
for a fixed hold delay
Fig. 5 shows a histogram of the measurements with astrontium source . The threshold of the TA Chip wasset to 13 mV which corresponds to a Charge-thresholdof 16 fC . Sinne only this channel was active in thetrigger the pedestal should be suppressed, which isnot the ease as shown in the histogramm . The high
pedestal peak could be due to noise-triggers in theTA-chip resulting in a rather weck trigger perfor-
malme for small energy-losses.The maximum energyloss of electrons in 300iim sili-con according to caiculations below 250 keV whilethe measurement shows a energyloss of 460 keV . Pile-
up in the detector can be excluded as reason for thisdeviation because the rate of electrons seen by theactive strip was too Iow in order to have dead-timeeffects.The reason for the incorrect energy measurement hasnot yet been determined, so further investigations
25
: 20
15pedestal
P
10IP
0
1
r--iLJ
-10
0
10
20
30
40
50
strip 70
fC
Figure 5 : Histogram for "Sr scaled in fC
have to be done, once a more flexible DAQ systemis available . For that purpose a new real-out sys-tem [4] is currently under development . lt will allowto evaluate both detector sides simultaneously.References:
Integrated Deteetors Electronics AS,http: //www.ideas .no.
Integrated Detectors & Electronics AS,VA32HDR technical information manual.
Integrated Detectors & Electronics AS,TA32C technical information manual.
[4] A. Mussgiller, "Readout for front-end Chips ofSilicon Strip Deteetors", contrib . to this report,p. 30.
1 PNPI Gatchina2 JINR Dubna
2000
1750 11500
1250 r1000
750 f- [ 1 1
[ 2 ]
[ 31
Design of a Vacuum-eompatible Read-out Board for the ANKE Vertex Detector
A. Mussgiller, S . Merzliakov and R. Schleichert
For the ANKE vertex detector a first vacuum-compatible read-out board is under development.Due to the heat generation in the front-end chip-combination VA32HDR [1, 2, 3] and TA32C [4], spe-cial attention has to be drawn to the cooling of thehybrid . Tab. 1 shows the thermodynamie propertiesof the two chips .
VA32HDRworking range -20°C to 40°Cheat generation 48 mWdimensions 3642pm x 3355pmheat flux 3934 W/m2
TA32Cworking range -20°C to 40°Cheat generation 27 mWdimensions 2421pm x 3325pmheat flux 2733 W/m2Table Properties of the front-end-chips
For the temperature-analysis the Finite ElementMethod software ANSYS [5] has been used . In afirst step, to verify the correctness of the simulation-program itself, the readout-board used by theBELLE-collaboration [6] has been modeled. As a re-sult it can be said that the temperatures given byBELLE [7] and the ANSYS-simulation differ in lessthen 0.1K.In a second step the first variant of an ANKE-hybridhas been studied . As bare-material AlO-ceramic hasbeen choosen . The chips will be glued on a copper-layer to ensure sufficient heat conductivity . Fig. 1shows one segment of the top-layer of the hybridwithout the wires for electrical connections . The hy-brid consists of 10 such segments, corresponding to10 chip-pairs or 10 * 32 silicon-strips with a pitch of200pm .
x
Figure 1 : top-layer and cut of one segment of thevacuum hybrid
A two-dimensional model of the hybrid is not ade-quate. For that reason a 3D-solid model has beenconstructed . The heat-generation by the chips issimulated as a heat-flux through the surface of theglue . The material properties used in the simulationare listed in Tab . 2 .
material heat-conductivity thiclmessin W/m . K in ;Im
AlO 25 760copper 393 35glue 1 .7 100
Table material properties used for the simulation
The surface of the heat-contact was held at a con-stant temperature of 0°C . Fig. 2 shows the temper-ature distribution along the x-axis on top of the ce-ramic board, under the VA32HDR, the TA32C andthe heat contact . In accordance with the vacuum con-ditions, heat-transfer by radiation is not allowed inthe simulation and thus the total heat generated bythe chips is transferred through the surface of theglue .
3
0 .005
0 .01
0 .015
0 .02
0 .025
0.03distance from edge of hybrid in m
Figure temperature distribution along the x-axisEven with an increase of the heat-generation insidethe chips by a factor of 2, due to possible radia-tion damage, the maximum temperature-rise belowthe chips stays below 5-6K . From the simulationsAlO seems thus suitable for the double-sided readoutboards for the ANKE silicon-vertex detector. Thefirst board will be equipped with one temperaturesensor to verify the simulation.References:[1] Integrated Detectors & Electronics AS,
http://www.ideas .no.Integrated Detectors & Electronics AS,VA32HDR technical information manual.A. Mussgiller, "Evaluation of front-end Chipsfor Silicon Strip Deteetors", contrib . to this re-port, p . 30.
[4] Integrated Detectors & Electronics AS,TA32C teehnical information manual.ANSYS, Inc ., http ://www.ansys,com.The BELLE-Collaboration,http://bsunsrvl .kek .jp.D. Marlow, "Heat Flow Estimates for GIO-based Hybrids for the BELLE SVD" .
]
[2]
[3 ]
[5][6]
[7]
33
PbWO4 as a scintillator material for a photon deteetor at ANKE/COSY
V.Hejny, R.Beck 1 , W.Döring2, R.Novotny2 , H.Ströher
Multiple photon detection is a successful tool atmany accelerators to identify neutral final states inmedium energy physics . At COSY experiments cur-rently focus on the detection of charged particles inthe final state with no possibility of direct identifica-tion of neutral final states . Therefore, it is intendedto build a dedicated photon detector around the tar-get point of ANKE [1] . Combination of the ANKEspectrometer and a photon detector will allow toperform more exclusive experiments by identifyingcharged and neutral partieles simultaneously.Building the detector for use with ANKE implies atleast two major constraints : lack of space aroundthe target and operation in the fringe field of theANKE dipole 0 .3 T) . To solve the latter prob-lern fine mesh PMTs (Hamamatsu 85505) are cur-rently tested . Use of photo diodes will not be pos-sible because an excellent time resolution is neces-sary for background suppression. The limited spacein the target region restricts the length of one detec-tor module to about 12 cm . Therefore, a scintillatormaterial with a radiation length X® as small as pos-sible is required . The whole detector should covernearly 4ir with a maximum diameter of 70-80 cm.Fig 1 shows a possib l e design of such a detector.
Figure 1 : Schematic view of a possible design of thephoton detector using 1060 modules . The figure isbased on an implementation in GEANT .
slightly tapered modules (0.4', 15 cm bong, 2 .2 cmx 2.2 cm endface) were arranged in a 5x5 matrix.They were coupled with optical grease to fast pho-tomuliplier tubes (Hamamatsu R3478, base : E2253-06) and operated in a temperature stabilized box(t 5.5°C) . During the test a photon energy rangebetween 66 and 790 MeV was covered . Due to theused PMT/base combination an unexpected non-linear energy calibration had to be applied in theanalysis to correct for saturation effects, which tim-ited resolution of the recontructed shower en-ergy. To compare the new results with former ones,only the response of the central detector of the arrayhas been taken into account . Fig. 2 shows the resultof such a comparison . In addition, the effect of theslightly increased endface (and therefore a decreasedfraction of light accepted by the same PMT) wastaken into account . The resolution of the new crystalsis significantly better than the first test matrix . Thisimprovement is connected with an increased lightoutput up to a total mean value of 4 .6 p.e ./MeV.There is only a small spread around this mean value,which refiects the improved reproducibility in pro-duction . The obtained time resolution is rf t = 130 ps.Based on these results. PbWO 4 appears to be anideal candidate for the scintillator material of theproposed photon detector.
PbWO 4 = 0.89 cm) is a well known mate-rial in high energy physics and will be used in theECAL/CMS calorimeter at CERN. Due to its Iowlight output tests were required to investigate itsusefulness at medium energies below 1 GeV. A se-ries of experiments with electrons [2] and taggedphotons [3] proved the applicability of PbWO 4 inthis energy range (o,-/E 1.54%/ x/E[GeV] + 0 .30%,
< 200 ps) . These results have been obtained usingcrystals with large inhomogenities and not Optimumoptical and scintillation quality.In a new test experiment, performed at the taggedphoton beam of the electron accellerator MAMIat the University of Mainz, improved Nb/La-dopedcrystals optimized for ECAL/CMS were used . 25
Figure
Energy resolution of the central detectormodule in comparison with previous measurements.
Referenees
[1] M . Wischer et . al, COSY LOI #83: A photondetector for COSY, May 1999.
[2] R. Novotny et al ., IEEE Trans . on Nucl . Sc . 44(1997) 477.
[3] K . Mengel et al ., IEEE Trans . on Nucl . Sc . 45(1998) 681.
1 Institut für Kernphysik, Universität Mainz2 11 . Physikalisches Institut, Universität Gießen
34
Status of the pellet-target preparation for ANKE*
W. Borgs, A. Boukharov a , M . Büscher, V . Chernetsky", V . Chernyshev a
The tests of the ANKE pellet target [1] have beencontinued at ITEP. As a result of these tests it isexpected to reach stable conditions for hydrogen-droplet production in the triple point chamber of themain cryostat . Furthermore, hydrogen pellets shouldbe observable in the first chamber with high vac-uum . After final tests at ITEP the target will bedismounted and transfered to the IKP of FZJ in thebeginning of 2000 . Then the target will be reassem-bled and tests will be continued . According to thecurrent time schedule it can be expected to start op-eration of the pellet target at ANKE in the middleof 2001.The results of the tests performed so far at ITEPcan be summarized as follows : The pellet target set-up has been assembled in the second half of 1999for experiments on hydrogen-droplet production ina special test-laboratory . Hydrogen and liquid he-lium supply systems were completely assembled andtested . Before a first füll scale pellet-target test sev-eral cycles of cryostat cooling to liquid nitrogen tem-perature have been performed in order to test pres-sure and temperature control systems.First target operation with hydrogen flow at liquidhelium temperature was achieved in November 1999.The cryostat and other systems of the target workedstable and close to the design parameters . About 1fiter liquid helium and 2 Biers of liquid nitrogen areneeded per hour for target operation.A second full-scale test run was performed in Decem-ber 1999. During this run a pressure of about 10 -5mbar in the first vacuum chamber has been achievedat a hydrogen flow of 10 1/hour through the sluicebetween the triple-point chamber the and first vac-uum chamber. However, the necessary temperatureconditions for stable droplet production were not ob-tained yet . This is most probably due to a too highthermo-conductivity of a stainless steel membranewhich separates the first vacuum chamber from thevacuum insulating volume. lt is planned to removeall possible sources of external termo-fluxes into thetriple point chamber and to finish the tests at ITEPduring January/February 2000.The infrastructure for the pellet target at ANKE wasdesigned completly and partly prepared in order tostart the work at COSY:
• The space for a full-scale target test at COSYwas prepared.
• A special support frame for target tests andpossible methodical research of pellet produc-tion was manufactured.
• The vacuum, cryogenic and hydrogen sup-ply systems for the pellet-target operation atCOSY were designed .
The vacuum and cryogenic equipment for op-eration at COSY has been ordered and mostparts have already been delivered.
• The development of additional CAMACelectronic-control units is in progress . All mod-ules will be ready in the end of 1999.
• The development of a PC control system andnecessary software for the pellet target set-upat ANKE is in progress.
In parallel to the preparation of the target set-upsystematical studies of eapillarssluices have been per-formed with help of a special test-cryostat at theMoscow Power Institute. The experimental valuesof the gas-flow conductivity have been measured forsluices with diameters 100, 200, 500, 700, 800 pm and50 mm length . These data are crucial for the finaldesign of the vacuum-pumping system. To better un-derstand possible deviations from triple point pa-rameters, the process of droplet-flux production atdifferent pressures in the triple point chamber hasbeen studied theoretically and experimentally . Dataon stable conditions of droplets production havebeen obtained [2] . The experimental results are inpreparation for publication . First results of vacuumand pellet-generation tests with a prototype targetwere presented during the international conferenceCRYO-98 [3].
References:
A . Boukharov, M . Büscher, V . Chernetsky, V.Chernyshev, "A pellet target for ANKE", An-nual report 1998 of the IKP, FZ-Jülich, 1999.
A . Bucharov, A . Ginevsky, A. Dmitriev, V.Chernetsky, V . Chernyshev, M . Büscher, W.Borgs, A . Semenov, "Theoretical calculationsand experimental study of stable droplet fluxproduction in critical conditions", PreprintITEP (in preimimtnm).
A . Bucharov, A . Ginevsky, A . Dmitriev,V . Chernetsky, V . Chernyshev, M .Büscher,W.Borgs, "Pellet target for experiments oninternal beam of accelerators", Intern . Conf.CRYO-98, Prague, May 1998.
'Institute of Theoretical and Experimental Physics,B. Cheremushkinskaya 25, 117259 Moscow, Russia.* Supported by grants RFFI99-02-18179a, INTAS98-500, DFG-443RUS-113, WTZ-RUS-643-96.
[1]
[2]
[3]
35
The Polarized Aton& Beam Source for the AN -Spectrometer
R.Baldauf 1 , R.Engels2, H.Kleines ' , N.Koch3, V.Koptev4, A.Kovalev4, P.Kravtsov4, S .Lorenz 3 ,
B .Lorentz, M.Mildrtytchiants5, S .lvhkirtytchiants4, M.Nekipelov 5, V .Nelyubin 4, H.Paetz genSchiecke , .Rathmann6 , J .Sarkadi l , H.Seyfarth, E.Steffens 3 , A.Vassiliev4 , K.Zwoll '
The present report, based on the previous Annual Report1998 [1], describes the recent progress in establishingand testing the polarized atomic beam source (ABS).
The rf dissociatorThe dissociator is completely assembled and has beentested in long-term operations . A Hüttinger 13 .6 MHz600 W rf generator [2] with a mach box is used topower the plasma . MKS flow controllers [3] are installedallowing primary H2 or D 2 inlet flows up to 8 .5 mbanl . s iland 02 admixture up to 0 .2 mbar-1•s 1 . The pressure inthe dissociator gas volurne is measured by an MKSBaratron gauge . These units are controlled via a fieldbus(PROFIBUS DP) by a PC based WinCC system runningunder Windows NT/98 [4] . The ABS beam has beenstudied for H 2 inlet flows up to 5 mbar-l-s'1 . Preliminarymeasurements of the degree of dissociation in the beamhave been carried out with 02 admixtures of the order of0 .1 atomic %.
The nozzle-cooling systemThe first basic tests of the setup have been performedwith a Cu heat bridge connecting the cryocooler(Leybold ROS 120 [5]) and the nozzle to be cooleddown to temperatures 60 to 120 K at a heating power byrecombination of atoms around 10 W. Due to itsappreciably smaller mass, a Ne heat pipe should allow
T0,1 q0,1
Fig. 1 : Relation between the heat transfer and thetemperature difference between nozzle (T u) and coldhead (T0 ) measured with the ABS Ne heat pipe (6 .2 cm 2lower, boiling surface) .
much faster nozzle-temperature variations [6,7], e .g . forheating up to clean the nozzle . Thus, after the firstsuccessful studies the Cu heat bridge has been replacedby a cryogenic Ne heat pipe . As an example of the firstmeasurements Fig . 1 shows the relation between thetransferred heat and the temperature difference betweenthe nozzle and the cold head of the cryocooler . Thethree regions A, B, and C correspond to bubble,transitional calunart, and surface-film (Leidenfrost)boiling, respectively . The measured curves also showthe expected hysteresis-loop behaviour . The valuesLiTer2=23 K and q,r2=23 W, measured at 12 bar Ne gaspressure, agree very well with the calculated values of26 K and 25 W, respectively.
The permanent sextupole magnetsThe six permanent NdFeB sextupole magnets have beendelivered by Vakuumschmelze [8] . Assembled from 24segments, made from 3 materials differing in remanenceand coercivity (VACODYM 510 , 383HR, 400HR),they yield the pole tip field strengths listed in table 1,which are in excellent agreement with the predictions ofMAFIA field calculations.
Table
The calculated and measured pole tip fieldstrengths of the sextupole magnets (dimensions in mm).
Magnet d ;naer d outer 1 B ocak[T] B u'[T]
1 10/14' 40 40 1 .633 1 .634(8)2 16/22 ' 65 65 1 .641 1 .684(6)3 28 94 70 1 .642 1 .625(4)4 30 94 38 1 .564 1 .565(2)
5,6 b 30 94 55 1 .605 1 .621(3)
a magnet with conical apertureb both magnets have identical dimensions, only the
field distribution of magnet 5 has been studied infull detail
Careful studies of the field distribution have beenperformed with a small Hall probe [9] of 200x 100area and 15 p.m thickness . The azimuthal distributions,measured near to the aperture surface, reveal 54- and102-pole contributions superimposed on the basic 6-pole distribution. This behaviour is due to the 24-segment structure and is in agreement with the analyticpredictions by Halbach [10] and the MAFIA calcu-lations . An example of the measured distributions isshown in Fig . 2.
ttT=30K T =60K T =30K
- zaT=8OK : T =120K, T 40K
P N. .. .12 bar (at cr2)
Lt-. :Idee
10
20
30
36
Fig . Azimuthal field distribution, measured at 0 .1 mmdistance from the aperture surface of magnet 5 (dots), incomparison with that from the MAFIA calculation (thinsolid line), the fit by the Halbach formula [10] with asfree parameter (not distinguishable from the data points),and the pure 6-pole distribution (dashed line).
Laser welding of the stainless-steel encapsulation is inprogress [11] . The magnets will be installed in thebeginning of 2000. A publication on the results achievedis in preparation.
The degree-of-dissociation measurementsThe device for the measurements of the degree ofdissociation with a crossed beam quadrupole mass
Elf
spectrometer (QMS) has been installed and tested[12,13] . As shown in Fig . 3, it is mounted on a two-dimensional manipulator, which facilitates to measurethe degree of dissociation of the beam and also todetermine the beam profile.
The rf-transition unitsThe weck and medium field hyperfine transition unitsfor hydrogen have been designed and manufactured[14] . The medium field unit has been installed. In orderto test its proper functioning, the homogeneous magneticfield strengths at a series of field-producing currentshave been determined by tuning the rf frequency to themaximum of polarization measured with the QMS . Thefield strengths, deduced from the resonance frequenciesand the theoretical hyperfine splittings, are in goodagreement with the values measured using a Hall probe[14] . Furthermore, the polarization has been studied as afunction of the applied rf power.
The device for beam-intensity studiesThese measurements will be carried out using acompression tube . The device has been built andinstalled [15,16] with the compression tube placed at thesame location as the feeding tube of the storage cell(300 mm from the exit of the last magnet) . Absolutebeam intensities and distributions will be measuredusing a combination of x-y and z manipulators (Fig .4)after installation of the magnets and rf-transition units.
WI
5
_h »
Fig. 3 : Sideview of the QMS device (1 : ABS chamber,2 : crossed beam QMS, 3 : cylindrical chopper, 4 : sup-porting flange,
rotary drive, 6 : preamplifier and HVsupply,
x-y table,
LED support) . The direction ofthe atomic beam is indicated by the arrow .
Fig. The setup with the compression tube (1), itsguidance tube (2), and support components (3 to 8) . Thetwo intermediate flanges are used to mount the hotcathode pressure gauge and the unpolarized calibrationgas inlet, respectively.
37
A special calibrated unpolarized gas feed system willpennit to measure the absolute beam intensity with anaccuracy of a few percent . lt also may be used to feed astorage cell for first measurements with unpolarized gas .
a protocol based on XDR and UDP to communicatewith the WinCC program and acquires additional datafrom directly connected devices such as the QMS or thewire monitor [19] . This software provides automaticmeasurements with the ABS.
Beam-profile measurementsA two-dimensional monitor of the atomic flow has beendeveloped [17] based on the recombination heattransferred to the surface of thin tungsten wires (Fig . 5).A prototype with 8x8 wires has been used to prove theapplicability of the method [18] . Preliminary results on
Atomic Hydrogen beam
H + H
H 2 +4 .'°7°S eV
surface recombination
Fig . 5: The principle of recombination heating on thesurface of thin wires.
the profile of the atomic H beam during the firstOperation times of the dissociator were obtained.
The slow control SystemThe slow control system is based [4] on the consistentuse of industrial technologies like SCADA (SupervisoryControl and Data Acquisition), fieldbus (PRO USDP), and PLC (Siemens S7) . To give an example for theperformance achieved, the system enabled degree-of-dissociation studies under füll automatic control . Atpresent the system processes 200 signals to and from avariety of pumps, valves, measuring devices, rfgenerators and PID controllers.
PC controlled parameter studiesThe ABS is controlled by WinCC software whichprovides UDP protocol service for remote operations.Special software was developed for data acquisition andABS control from a remote Windows computer . lt uses
Beam polarimetryThe first measurement of beam polarization has beenperformed in a temporary setup . Two magnets with thedimensions of magnet 1 (table 1) with pole tip fields ofabout 1 .15 Tesla were installed before and behind themedium field transition unit. The polarization of about28%, measured with the QMS, agrees with theprediction of trajectory caiculations . lt is planned in thefuture to use the Lamb-shift polarimeter which is underconstruction at the Universität zu Köln [20].
' Zentrallabor für Elektronik, FZ Jülich2 Universität zu Köln , D-50937 Köln, Germany' Universität Erlangen-Nürnberg, D-91058 Erlangen4 PNPI Gatchina, 188350 Gatchina, Russia5 now PhD students from PNPI Gatchina6 Universität Erlangen-Nürnberg, working at
Jülich
References:
[1]R. Baldauf et al ., IKP Annual Report 1998, reportJül-3640 (Berichte des FZ Jülich, 1999), p .23
[2]Hüttinger Elektronik GmbH, D-79110 Freiburg[3]MKS Instruments GmbH, D-81829 München[4] H. Kleines et al ., in : Proc . Int . Conf. on Accelerator
and Large Experimental Physics Control Systems(icaleps 99), Trieste, October 4-8,1999 (in print)
[5]Leybold Vakuum GmbH, D-50968 Köln[6] A. Vassiliev et al ., PNPI report NP-32-I997, 2175[7] A. Vassiliev et ah, in : Proc .
Int. Workshop onPolarized Gas Targets and Polarized Beams,Urbana/IL 1997 (AH" Conf. Proc . 421, 1997), p .4°79
[8] Vacuumschmelze GmbH, D-63450 Hanau[9] made available by V . Pogodin, A . Joffe Physical-
Technical Institute, St .Petersburg, Russia[10] K. Halbach, Nucl . Instr . Methods 169, 1 (1980)[11] Fraunhofer-Institut für Lasertechnik (ILT),
Abt . Mikrotechnik, D-52074 Aachen[12] M. Mikirtytchiants, diploma thesis (St. Petersburg
State Technical University, 1999)[13]M. Mikirtytchiants et al ., in: Proc . Int . Workshop
on Polarized Saumes and Targets (PST99),Erlangen, September 29-October 2, 1999 (in print)
[14] S . Lorenz, diploma thesis (Universität Erlangen-Nürnberg, 2111l)
[15]M. Nekipelov, diploma thesis (St. Petersburg StateTechnical University, 1999)
[16] M. Nekipelov et al ., as ref. [13][17] A. Vassiliev et al ., PNPI report EP-46-1998, 2260[18] A. Vassiliev et al ., as ref . [13][19] P. Kravtsov et al ., as ref . [13][20] R. Engels, PhD thesis (Universität zu Köln)
38
A Lambshift polarimeter for the polarized target at ANKER. Engels*, R . Emmerich*, J . Ley*, H . Paetz gen. Schieck*
A Lambshift polarimeter for the mea-surement of the nuelear polarization ofan atomic beam of hydrogen(deuterium)from an atomic beam souree is under con-struction . With this polarimeter it is pos-sible to measure the polarization of a pro-ton (deuteron) beam as well as the polar-ization in a storage cell.In the first step the atomic beam is ion-ized in a strong magnetic Feld (>0 .2 T)to preserve the polarization . The ionizeris finished and the expected efficiency of10' was reached.With a simple Wienfilter the nuelear spincan be rotated into the (horizontal) beamaxis of the polarimeter . Thus the H orD atoms are separated from backgroundions produced in the ionizer.Again a strong magnetic Field is impor-tant for the production of polarized me-tastable hydrogen (deuterium) in a Os-eell . With a compact coil design a B Feldof more than 0 .2 T was obtained.A spinfilter separates single hyperfine sta-tes . Only metastable atoms with a knownnuelear spin are transmitted as a functionof the magnetic field in the spinfilter.In the last component the remaining me-tastable atoms are quenched into thegroundstate by a strong electric Field . Theemitted Lyman-a light (121 nm) is col-lected by a photomultiplier.The polarization of the atomic (ion) beamcan then be deduced immediately fromthe number of photons in the peaks cor-responding to the nuelear substates +1/2for hydrogen (0, +1 for deuterium) . Fordeuterium the vector and tensor polar-izations are obtained simultaneously.
Ly - a spectra from tests with unpolar-ized ion beams of protons and deuteronsare shown in figures 1 and 2 .
Figure Ly - a spectrum of an unpo-larized proton beam as a function of thespinfilter B Feld
=o=n
am 1 -1
520
5450
580
600
620
Opinfilter B-fitld [G 6g
Figure Ly - a spectrum of an unpo-larized deuteron (proton) beam as a func-tion of the spinfilter B Field
To measure the polarization of the ver-tical beam of the ABS for the polarizedtarget at ANKE a 90 ° deflector is inpreparation.
*Institut für Kernphysik, Universitätzu Köln, D-50937 Köln
References:[1] R. Engels, R . Emmerich, J . Ley, II.Paetz gen . Schieck, Proc . Int. Workshopan "Polarized Sources and Targets", Er-langen 1999
D:2
39
A-production at irre, 80 MeV ahmte Threshold at COSY-11
S .Sewerin for the COSY-11 Collaboration
Inspired by the successfully performed measurementsof the A-hypemn production close to threshold [1-3],COSY-11 has extended its program to E°-production [4]and observed an unexpected Iarge cross section ratio .
reaetion channels and to observe the transition from aA/E"-ratio of about 28 at threshold to . tut 2-3 at excessenergies > 300 MeV.
1 .2 t25so
Fig . Missing mass spectrum at an excess energy of 12 .9MeV above the E° threshold . Production of the A-
d the E 0-hyperon is visible ve a continuousbackground.
Sirrmltaneously to the near-threshold E°-production, A-production at excess energies of . 0 tut 80 MeV was de-tected. Though the acceptance at 80 MeV is only in theorder of 10 -4 , a Iarge amount of A-events could be identi-fied as shown in Fig . 1 . A detailed discussion of the con-sequences of the low acceptance is given in [5].
Fig . Angular distributions of the A-events of Fig . 1.
Acceptance corrected angular distributions of A-produc-tion events are shown in Fig . 2 . Legendre-polynominalfits to these distributions have been performed. The de-termined a2 /ao-ratio is shown in Fig. 3 . The angular dis-tributions be integrated to caleulate the total emsssections . The extracted values are shown in Fig . 4 to-gether with observed close to threshold at COSY-11and at excess energies of 55 MeV and 138 MeV at theCOSY-TOF experiment [6] . Due to the Iow acceptancesystematical errors might occur, but the observed crosssections are qualitatively in g
a eement with COSY-TOF .COSY- 11 will extend these measurements of E° and A-production to higher excess energies in order to extraetthe energy dependence of the cross section ratio for both
Fig. Values of the a2 /a°-ratio determined by Legendre-polynominal fite to the angular distributions fromFig . 2 are plotted as filled symbols . The open sym-bols correspond to COSY-TOF dato ..
Fig. 4: Total eross sections of the reaction pppK+A . Data measured at COSY-11 are shownas circles, values ob `ned at COSY-TOF [6] areplotted as squares.
Reforenees:
[1] Balewski et ah, Phys . Lett . B388 (1996) 859[2] J . Balewski et al ., Phys. Lett . B420 (1998) 211[3] J . Balewski et a1 .,Eur. Phys . J . A2 (1998) 99[4] S. Sewerin et al., Phys. Rev. Leu. 83 (1999) 682[5] S. Sewerin, PhD thesis (1999), Rheinische Friedrich-
Wilhelms-Universität Bonn[6] R. Bilger et ah, Phys . Lett. B420 (1998) 217
2
0o 20 so
40
Studies on the Reaction pp-4 ppK+ K+ dose to Threshold at the COSY-11 Facility
T. Listcr*, C . Quentmcier*, M. Wolke for the COSY-11 Collahoration
At the COSY-11 facility mcasurements on the re-action pp -4 ppK+ K+ have heen performed. Up tonow, the COSY-11 collahoration has detormined up-per limits on thc total oross section at several heamenorgics dose to threshold [1-3].In the last two ycars additional dato with higherstatistics have heen haken. At an exccss energy ofQ= +17 McV a significant numher of events has heenohserved, which cm be identified with the final statcpp -4 ppK+K + .At the COSY--11 detection system the four-momenta of positively charged particles arc ex-pcrimontally detormined . For the reaction pp -+ppK+K+ the missing mass of the ppK+ -systom cor-responds to thc mass of the K+ --meson. In reactionsof thc type pp -› ppK+ X olle proton and particle(s)X may originate from the decay of a previously pro-duced hyperon Y in pp -+ pK+ Y -+ pK+pX . In thiscase, thc missing mass distribution with rospect tothe ppK+-systern shows up as a hroad distribution,ending at the kinematic Limit.
Missing mass' (ppK+) [Gev' !c4 1
Figure 1 : Squared missing mass spectrum.
In figure 1 thc squared missing mass of the systemppK+ is shown . A significant signal at the squaredmass of the K+ -- meson can clearly he separatod fromthe hackground . Additionally, with reduced accep-tancc the missing K+ -moson can bc detoctod hy ascintillator and a silicon pad detoetonWith thc now dato the total oross section for thepp -4 ppK+ K + reaction 17 MeV ahove thresholdand an additional upper Limit at an excess onergy ofQ= 3 MeV have heen extracted and arc shown as
very preliminary estimates in figure 2 . The crror isa very conservative gucss.
Figure 2 : Upper limits on the total cross section forthe reaction pp -4 ppK+K+ at a confidence level of95% . The Limit at Q= 3 MeV and the conservativelyestimated cross section range at Q= 17 MeV are verypreliminary.
References:
[1] M. Wolke, PhD thesis, Rheinische Friedrich-Wilhelms-Universität Bonn (1997) Annual Re-port 1996, IKP, Forschungszentrum Jülich, Jül-3365 (1997) 42
[2] T. Listen PhD thesis, Westfälische Wilhelms-Universität Münster (1998)
[3] Annual Report 1998, IKP, ForschungszentrumJülich, Jül-3640 (1999) 36
* Institut für Kernphysik, Westfälische Wilhelms-Universität Münster, 48149 Münster, Germany
0
0
41
Energy Dependence of the Total Cross Section for the pp pp n° Reaction
close to the Kinematihal Threshold
P. Moskal* for thc COSY-1l collahoration
The first published total cross scction values for thepp nm' reaction near the kinematical thresh-old [1,2] triggercd a lange interest in explaining theunknown dynamics of the n' meson creation in thcproton-proton collision [3-8] . The dato, enahled alsofirst infercnces about the proton-n' interaction . Asteep deeroase of the total cross scction when ap-proaching the kinematical threshold, indicated thatthis interaction might hc repulsive [9].
5
10 15 20 25 30excess energy in CM [ MeV ]
Figure 1 : Total cross scction of the pp -+ pprI' re-action as a function of the oenter-of-mass excessenergy. Open triangles and squares am from ref-crences [1] and [2], respectively. Filled eirdcs indi-cate the results of thc analysis of the COSY-11 mea-surements pcrformed in 1998 [10] . Statistical andsystematical crrors are separated hy dashes. Thcsolid line depicts caIculations of the total cross scc-tion assuming thc primary production amplitude tohe constant and only proton-proton interactions totakc plahe in the exit channel . Thc proton-protonscattcring amplitude was computed ahcordhIg to thcformulas from rdcreme [11] . Thc obtained energydopendome agrees well with thc Fiildt and Wilkinmodel [12].
Hore report new results ohtained from thc anal-ysis of the dato, [10] taken in 1998 with a stoohasti-oally cooled proton heam at thc Cooler SynchrotronCOSY. Total oross sections for the pp
ppn' re-action wem. determined at eight different excess en-ergy values ranging between Q 1 .53 MeV andQ = 23 .64 MeV. Tim total integrated luminosity ob-tained during the two weeks of heam time amounted
to 1 .4 A -1 .Figurc 1 shows the compilation of all available datefor the near-threshold meson production via thepp -+ pprl' reaction . Thc new results, presented asfilled drdes, are well descrihed hy the integral ofthe phase-space volume weighted with the squaredproton-proton smteering amplitude . This indicatesthat the influence of the proton-n' FSI on the energydopendome of the total Cross scction is too weck tohe seen within the up-to-date experimental accu-racy. Thus, in view of the new results, former spec-ulations on the repulsive interaction between the rl'meson and the proton appear to he doubtful.Thc determination of differential cross sections wouldbe very useful to learn more about the proton-n'interaction.
Reforenees:
[1] F. Hibou et al ., Phys . Lett . B 438 (1998) 41
[2] P. Moskal et al ., Phys . Rev . Lett . 80 (1998) 3202
[3] K. Nakayama et al ., Preprint FZJ-IKP-TH-1999-24 (1999), e-Print Archive nucl-th/9908077
[4] V. Bernard, N . Kaiser, Ulf-G . Meißner, Eur.Phys . J . A 4 (1999) 259
[5] E. Geslahn, A . Moalem, L. Razdolskaja, Nucl.Phys . A 650 (1999) 471
[6] A . Sihirtsev, W. Cassing, Eur . Phys. J . A 2(1998) 333
C. Wilkin, Baryons'98, Bonn, Germany, 22-26 Sep 1998, proo, of tic conf, World Scien-tific, Singapore (1999) ; e-Print Archive nud-th/9810047
A . Sihirtsev, W . Cassing, e-Print Archive nucl-th/9904046
V. Baru et al ., Eur . Phys. J . A 6 (1999) 445
P. Moskal et al ., Annual Report 1998, IKP,Forschungszentrum Jülich, Jül-3640 (1999) 32
[11] B. L. Druzhinin, A. E. Kudryavtsev, V . E.Tarasov, Z . Phys. A 359 (1997) 205
[12] G. Fiildt, C . Wilkin, Phys . Lett . B 382 (1996)209
* Institute of Physics, Jagdlonian University, 30-059Cracow, Poland
1
10 2 7
[ 7]
[ 8]
[ 9]
[10]
42
Energy Dependence of the Primary Production Amplitude for the pp -+ ppri ' Reaction
P. Moskal* for the COSY-11 collahoration
New date on and ri' meson production in thcpp -+ ppX reaction, obtainod recently at thc COSY-11 facility [1], encouraged us to continuc [2] the phe-nomenological investigations on the energy depen-dencc of the primary production amplitudo . Themodulus IMo 1 of thc primary production amplitudewas calculated [2] under the assumptions that thisquantity is independent of the incoming proton hcamenergy, and that thorc is no final statt interaction he-tween the produced meson and protons.
2.52.25
21 .75
Figure 1 : a) Squarc of the proton-proton scatteringamplitudc from ef. [3] (solid), [6] (dashed), and [5](dotted) . h) Quantity lMol cxtractcd from the ex-perimental data (sec references in [1]).
In the dcrivation of lMo the enhancement from theproton-proton FSI, IMplin. 1,p l 2 , was calculated asan inverse of the squared Jost function, with theCoulomb interaction taken into account (sec solidlifte in Fig. la) [3] . Ohtained valucs for the quan-
tity lMol for ri and production are shown inthe Iowcr, middle and upper part of Figure lb, rc-spoctively. Thc shown values are normalized to unityat thc point of highest excess energy, for each me-son separately. If the assumptions in the dcrivationof llWo wem fulfilled thc obtainod values would heconstant as depicted hy the solid lines . lt can bcseen, howevcr, that in the case of thc ri meson, I M° I
grows with decreasing excess energy. The ohscrveddeviation from unity is too largo to he assigned tothe actual variation of the primary production am-plitudo . The caIculations of Moalcm et al . [4] showthat in the discussed energy rangt the primary pro-duction amplitudc may grow hy a few per cont only.Tbadam, thc obsorvod hehavior of 1Mol may he as-signed to an attractivc rl-proton interaction . In thedato, for the 7r ll production, apart from the two low-ost points one can notice a tiny growth of 1Mo 1 whenthc excess energy decreases from Q
20 MeV toQ = 2 MeV. This is much smaller than in themeson case . Nation, that also the S-wavc 7r-protoninteraction is much weaker than the r)-proton one,Similarly, nnglocting the two lowest points for the
meson, one observes about 20 % ineroase of lMulwhen approaching the threshold . This might indi-cate an attraotive ri'-proton interaction . Wc musthe careful, howaror, since the hohaviour of 1Mol de-ponds on the prescription uscd for the proton-protonscattcring amplitudo, and as can hc seen in Figure lathere exist modeln, which differ significantly. Them.
-forc as a next step wc would like to check thc sensi-tivity of lMol to the uscd prescription.
References:
[1] J. Smyrski et ah, to bc publ . in Phys. Lat . B,e-Print Archive nucl-ex/9912011 : P. Moskal etal ., c-Print Archive nucl-cx/0001001
[2] P. Moskal et al ., Annual Report 1998, IKP,Forschungszentrum Jülich, Jül-3640 (1999) 35
[3] B .L . Druzhinin et al ., Z . Phys. A 359 (1997) 205
[4] A . Moalem et ah, Nucl . Phys. A 600 (1996) 445
[5] J . A. Niskanen, Phys . Lat . B 456 (1999) 107
[6] J . P. Naisse, Nucl . Phys . A 278 (1977) 506
* Institute of Physics, Jagellonian University, 30-059Cracow, Poland
2 .52 .25
21 .75
1 .51 .2S
10.75
PP PP 11
PP --. PP 11'
1
1 .51 .25
10.75
pp pp .0
0 .5 . 5
10 15 20 25 30excess 8neegy in CM [ MeV h)
43
Determination of the COSY Proton-Beam Dimensions
hy means of the COSY-11 Detection System
P. Moskal* for Hic C0SY-11 callaberation
At thc C0SY-11 facility [1] (sec Fig . 1) the produc-tion of short-living unchargcd mcsons, likc rl, w,or qS, is invostigatod hy mcans of thc missing masstechniquc in the pp -4 ppX roaction . Thc accuracy
natural width of thc mcasurod mcsons, providod thatthe hoam momentum spread is known as well . Thcknowlodgo of the dimonsions and relative settings ofbcam and target is also crucial for the determinationof the acceptance of the detection system.
Figurc Schcmatic view of the C0SY-11 detectionsctup. Only detoetors um:1 for thc mcasuromont ofclastically soattcrod protons am shown . Numhers, atthe silicon pad &Motor (Si) and helow the scintilla-tor hodoscopc (Si), indicate thc order of segments.Dl and D2 denote drift ohambors . Tim Xsi axis isdcfincd such that thc ferst segment of thc S1 ends at80 cm and thc sixtcenth ends at -80 cm.
of thc missing mass dotcrmination, which decideswhether thc signal from the given meson is visihleover a multi-pion hackground, doponds on the accu-racy of tim momentum roconstruction of thc rogis-torod protons, which in turn doponds on thc detec-tor resolution and thc momentum- and geometricalsprcad of the proton boam . Thc momentum recon-struction is performed hy tracing hack trajcctoriesfrom the drift chamhers through the dipolc magneticfield to the target, which is assumed to he a verti-cal line . In rcality, however, reactions take place inthat region of finite dimonsions wherc hcam and tar-gct overlap (sec Fig . 2) . Therafora, assuming in theanalysis an infinitesimal target implics a smearingout of the momentum vectors and hencc of the miss-ing mass signal . lt is not possiblo to determine thevcrtex of the reaction on an ovent-hy-cvcnt Basis andto correct for this offoot . Howevcr, if tim Heget andhoam dirnensions werc known it would he possihlc todetermine thc avorago smcaring of the missing massoriginating from this offoot and hcnce to inkr the
*Institute of Physies, Jagellonian University, 30-059 Cm-seih Poland
Figure Schcmatic description of the relative boamand target setting. Seen from ahove (upper part),and from asidc (lower part), and a.Y denote thehorizontal and vertical standard deviation of thc as-sumed Gaussian distribution of the proton beam den-sity, rospostivoly. Tim distancc botwoon the middlcof the proton bcam and the target centrc is descrihed
as Ax.
In this Import wo present a method of estimating thedimcnsions of the COSY proton boam hased on themomentum distribution for clastically soattcrod pro-tons, which arc always mcasured simultancously withthc invostigatod maction . Thc part of the COSY-11detection setup usod for thc registration of clasti-cally ssattcrod protons is shown in Figurc 1 . Thctwo hody kinematics gives an Imambignans rolationbotwcon thc recoil angles 0 1 and 02 of hoth soat-torod protons (sec Figure 1) . Therefore, as can heseen in Figure 3, the events of clastically soattorodprotons can bc idontifiod from the correlation lincformcd botwoon the position in the silicon pad dc-tector Si and the scintillator hodosoopo Sl . For theproton scattorod in forward direction and dofloctod inthe magnctic field of the dipolc the momentum vec-tor at the target point can hc determined . Accord-ing to two-hody kincmatics, momentum componentsparallel and porpondicular to the heam axis shouldform an ellipse, with a section shown as a solid line
Figurc Pad numbor of thc silicon detcctor Si ver-sus the Position in the S1 detector . Note that thenumbor of cntrics per bin is given in a logarithmicscale.
in Figure 4, which also prosorats data scloctod accord-ing to thc darrelation critcrion from Figure 3 . Themcan of data is clearly shifted from thc expected lins,reconstructod momenta am an avcragc langer thanoxpoctod . This observation can not he oxplainod,ncithcr by a wrang estimation of the proton bcammomentum, nor by a wrong assumption of the pro-ton bcam angle . In ordor to correct for this effect thebcam momentum must havo bocn changod hy man'than 120 McV/c (dashed linc in Figurc 4), which is40 times morc than the conscrvatively ostimatod or-ror of the absolute bcam momentum (± . 3 McV/c).Similarly, the effect rould havo boon corrected bychanging the heam angle hy 40 mrad (sec dashochdottod lins), which also cxceeds thc admissihlc dovi-ation of the bcam angle (± 1 mrad [3]) by at least afactor of 40.However, the obsorvod discrepancy can he oxplainodhy a shift of the assumod reaction point of -0 .25 cmin the direction perpondkul<ar to the heam, along theX-axis dofinod in Figurc 1 . Tbc momentum com-panents obtainod under this assumption, shown inFigure 5, agree with thc cxpectation depicted hy thesolid lins, and the date am now sprcad symmctricallyaround the theoretical lins . This sprcad is primarilydue to the approximation of a point-like target, andalso, hut to a much smallcr extent, due to multiplescattering and the sprcad of the heam momenturn.The last two effects cause a dispersion in the orderof the lins thickness.Assuming thc target to bc descrihed by a cylindri-cal pipe homogencously Mied with protons, and thcproton heam density distribution hy Gaussian func-tions with standard deviations c' X and cry for thchorizontal and vertikal directions, respectively, woperformed Monte-Carlo simulations varying Ax ando-x (sec Fig . 2) . Thc simulated events wem. storedand analysed in the same way as the experimental
Figurc Perpendicular versus parallel momen-tum components with respect to the heam direc-tion of particlcs registcrod at a bcam momentumof 3 .227 GeV/c. Thc numbor of entriss per bin isshown logarithmically. Thc solid live corresponds tothe momentum c11ipso expected for protons scatteredelastically at a bcam momentum of 3 .227 GeV/c,the dashed linc refers to a bcam momentum of3.350 GeV/c, and the dashed-dottcd lins shows themomentum ollipsc obtainod for a proton bcam in-clinod hy 40 mrad.
Figurc Same dato, as shown in Figurc 4 but anal-ysod with the target point shifted hy -0.25 cm per-pendicularly to the heam direction (along the X-axisin Figurc 1) . Thc solid linc shows the momentumcllipso at a bcam momentum of 3 .227 GeV/c.
dato. Thc comparison of the date from Figurc 4with the corresponding simulated histograms allowedto determine the horizontal proton bcam extension
and the relative shift of target and bcam Ax.Figurc 6 shows the logarithm of the ohtained x 2 asa function of thc valucs of 0»x and Ax assumed inthe Montc-Carlo calculations : A vallcy with a mini-mum is clcarly rccogniza,blo, which gives the uniquepossihility to determine the varicd parameters oxand Ax. Thc minimum of the x 2-distrihution, ato-x = 0.15 cm and Ax 0 .3 cm, is bottcr seen in Fig-
2 .4
2.6
2.8P li [GeVlc]
-1 .22 .2
45
ures 7 and 8, the x2 was calculatcd according to [4]:
X2 = [2(N, - Nn + 2 . MIn(Ni7N:)1 (1)
whcrc
and
(knote the content of thc i th binof the
spedrum dotorminod from ex-porimont (Fig. 4) and simulations, rospoctivoly.
Figure 6 : x2 as a function of ax and dx .
the horizontal plane is usod, whilc the vertical com-ponent romains a frec paramotcr . As shown in Fig-ure 9, the reconstructed distribution of the vcrticalcomponont of the reaction points indecd can he welldesoribod by a Gaussian distribution.Thc effect of a possiblo drift chambor misalignment,i . o. an inexactness of an angle a in Figure 1, wasestimated to oausc a shift in the momentum planecorresponding to a valuo of 0 .15 cm for dx . Thisgives a rather largo systematical blas to thc estima-tion of the absolute vorne of Ax, but it does not influ-onco the implioations concerning the paramctcr ctx.Changes of the hcam parameters during the 60 min-utos measurement cyclc werc also neglected . A morsdetailed analysis studying hcam condition ohangcsduring the erde - from heating the hcam duc tosoattcring in the target and from stochastically cool-ing the hcam - is in progress . Prcliminary resultsshow, that the hcam shrinks during the cyclo in thehorizontal plane, and simultancously broadons in thcvertical one.
UU-Lit-2UC:rl 00000
0 01D =EM=t380520C10O000.
cc 0 0 0 C2CIOCI82 080 00000
o CO C2 0 53 0CO 820
cl 0 82 C2 C3 C118 to 0000
rx
83 0o 0
• ci82
ra
03 0 08 4 0 0. CH 0
co• 5!. .9A2 .C:f
0.1
0 .2 0.3 0 .4 t:U. 0.6GJ cml
0.1
0.2 0.3 0.4 0 .5 0:6ax [cm1
4
3
Figure 7 : x 2 as a function of ar x.
, . . r-0 .8
-0.6
-0 .4
-0.2ex [cmj
Figure 8 : x 2 as a function of d
Thc vertical hcam extension of ory=0.53 cm was os-tablishod directly from Hic distribution of thc vcrti-cal componont of the particle trajectories at thc cen-tre of the target . This is possiblo, since for the mo-mentum reconstruction only thc origin of the track in
Figure 9 : Distribution of the vertical component ofthe rcaction points determined by tracing hack tra-jectorics from thc drift ohambers through the dipolcmagnetic ficld to the contro of thc target (in the hor-izontal plane) . "Tails" are duc to secondary scatter-ing an the vacuum ohamber and wem. paramotrizodby a polynomial of second ordor . Thc solid lins showsthc simultarmous fit of the Gaussian distribution andthe polynomial of second ordor.
References:
S. Brauksiope et ah, Nucl . Instr . & Moth. A 376(1996) 397
[2] H. Dombrowski et
Nucl . Instr . & Moth . A 386(1997) 228
[3] D . Prasuhn, private communioati ns.
[4] S. Bahr, R . Cousins, Nucl . Instr . & Meth. 221(1984) 437
10
46
Production of wesons at COSY-11
D . Grzonka, P. Kowina*, G . Schepersfor the C0SY-11 collaboration
The study of vector meson (V) production is veryimportant for a better understanding of the hadronicinteractions in the medium energy range . Of spe-cific interest is the elementary reaction pp -4 pp Vwhich may supply information about the NNV ver-tex functions, in particular the coupling constants.Furthermore due to the large masses of the vector-mesons a fairly large momentum transfer is requiredin the production process and therefore the nucleon-nucleon interaction will be tested at relatively shortdistances . The amplitude of the elementary vector-meson production reaction is, of course, needed as In-put for any more microscopic studies of vector-mesonproduction in light- or heavy-ion collisions.
To extract fundamental data like coupling con-stants the knowledge of the production mechanismis a prerequisite. For a separation of the contri-butions from different exchange currents total crosssection data are not sufficient, differential observ-ables are needed . For example, a theoretical studyof the w production ithin a meson exchange model
Figure Missing mass distribution for excess ener-
by
wgier e of 25 and 107 MeV . The dashed lins in theNakayama et al . [l] has shown that the angular
distribution is a sensitive observable to discriminate
spectrum
a dominance of mesonic or nucleonic eure
tributionnk at e=25 MeV indicate the background dis-
rents .
O.B 0.7
Figure 1 : Distribution of cos ecm, i .e . the wemission angle in ease of an w-event, versus thesquared missing mass at an excess energy of 107MeV. The w-production results in the band at about0 .61 GeV 2/c4 .
50 and 107 MeV . In total about 10 3 (e = 25 MeV) to10«€ = 107 MeV) w-events were detected . In spiteof the high excess energies the detection effieiency atC0SY-11 is high enough to cover the whole angularrange with a sufficient number of events . The dif-ferential detection efficiency is demonstrated in fig .1showing the distribution of the 'missing particles CMangle' given by the emission angle of the two protons,i .e . the CM (Center of Mass System} angular distri-bution of the w in esse of a pp -4 ppw-event, versusthe squared missing mass.
In fig .2 the missing mass distributions for themeasurements at = 25 and 107 MeV are shown.A clear w-peak is visible but the background levelresulting from multi-pion channels and p-productionis rather large. In order to separate the differentialdistributions of the w-events from the backgroundeffects, detailed Monte Carlo studies are presentlyperformed . Of course also total cross section valueswill be extracted which are up to now not known inthis excess energy range.
* Institute of Physics,Silesian University Katowice, Poland
References
At the COSY-11 installation the reaction
[1] K . Nakayama et al ., Phys . Rev. C57, 1580 (1998).pp -4 ppw has beeil measured at excess energies of 25,
47
Near-Threshold Meson Production in Proton-Proton Collisions
J . Smyrski* and P. Wüstncr t for the COSY-11 collahoration
Thc role of various meson exehanges as well as inhu-enees of final state intcraction (FSI) in thc rt mesonproduction in proton-proton collisions, am still notwell known. Existing dato on the pp -+ ppri reaction,originating from measurements at SATURNE usingthe speetrametors SPES-3 [1] and PINOT [2] and atCELSIUS [3] with the PROMICE/WASA detectionsystem, still leave enough frcodom for interpretingthe energy dopondonoc of Hic cross sections . There-fore, the COSY-11 collaboration performed mca-suromonts of the pp --* ppri reaction dose to thresh-old, whorc the FSI effccts arc ospooially largo.Measurements were performed in a slow ramp-ing mode with the hcam momentum varicd con-tinuously in the nanu from 9 .6 MeV/c bolow to20.4 McV/o abovo threshold momentum which isequal to 1981 .6 MoV/e. For the dato analysis, thisrangt was divided into 2 MeV/c intorvals . Tbc num-bcr of events corresponding to 7) production was dc-rived from the missing mass spectra . The hcammomentum was determined by shifting the 7)-mesonmass extracted from the missing mass spectra to itsvaluo known from the fitemtune . Tim derived cor-rection to the nominal COSY hcam momentum wasequal to Llip = -1 .88±0.80 MeV/c . An extrapolationof the mcasurod pp -+ pph counting rate towards thereaction threshold - in analogy to Rof. [4] - resultsin a correction valuc of -1 .89 ± 0 .78 MeV/c whichis in very good agroomont with thc shift in hcam en-ergy ohtained from the reconstructed ri mass . Thesimultancous measurement of olastic proton-protonovonts was um:1 to determine the luminosity and tonormalizc the rp production cross sections.Tbc valuos of the total cross sections arc shown inFig. 1 as a function of thc excess energy e . In firstorder thc energy clopondence in the threshold regionis closcribcd hy the availablo phase-space modified hythc FSI. The FSI can faotorimd into pp (f p)and pri (fp71 ) factors and the cross scction is given hyintegration over the availahle phase-space volumc p3 :
fPP(qpp) fpn(qp i u) fp,I (qv.,u)dp3(1)
whorc rip p is the relative momentum of the two pro-tons and
and qp2T, am relative momenta of themeson with respect to the first and second proton,
rcspoctivcly. The enhancement factors for theproton FSI were calculated using thc cffoctivo-rangoapproximation with tim complex h-proton scatter-ing length aup = 0.717 + i0 .263 taken from Ref . [5]and the complex h-proton effective rangt parameterr,tp = -1 .50 - i0.24 from Ref . [6] . The calculations,shown as a solid lins in Fig . 1, descrihe the exper-imental dato very well in the whole range of excess
energy. Omission of the n-proton FSI leads to disscmpondes with the dato as shown by the dashedcurve . While the error on the male of the excess en-ergy dopictod in Fig. 1 rcfcrs to thc unccrtainty ofthe absolute hcam momentum, the relative uncer-tainty of the hcam energies is helow the symbol size.Within this relative accuracy a caloulation mgkotsing the proton-proton Coulomb interaction (dottedcurve) fails to roproduoc the energy dcpendencc ofthe dato.
Figure 1 : Total cross sections for the rcaction pp -ap near threshold . Curves am dosoribod in the text.
References:
[1] A. Boudard, Few-Body Systems Suppl . 8 (1995)287
[2] E. Chiavassa et al ., Phys. Lat. B 322 (1994) 270
[3] H. Calen et al ., Phys. lieft . B 366 (1996) 39
[4] J . Balewski
al ., Phys. Lütt . B 420 (1998) 211
[5] T.-S . H. Lee, Physica Scripta 58 (1998) 15
[6] A. M. Groom S . Wycech, Phys. Rev. C 55 (1997)R2167
* Institute of Physics, Jagellonian University, 30-059Cracow, Polandt Zentrallabor für Elektronik, ForschungszentrumJülich, 52425 Jülich, Germany
48
Missing Mass Resolution in Near-Threshold Measurements
3 . Smyrski* for the COSY-11 collaboration
In thc COSY-11 oxporiment, the identification ofmesons produced in proton-proton collisions is per-formod using the missing mass mothod . lt was ob-sorvod, that thc missing mass distribution always
60
p,=1 .997 GeV/cbroadcns with incrcasing cxcess energy (sec cxam-
o 40
e = 4.7 mevple of missing mass spectra shown in Fig . 1) . This
20bchaviour is due to a kinematical offoct :
0In the CM-system, thc missing mass squared can he
60mitten as :
40
(ETOT - E1 - E2) 2 -
152) 2 ,
(1)
20
whorc ETOT is the total energy, E2 arc thc ener-gies of thc two outgoing protons, andli'1 ,15i2 arc theirmomentum wietors . In thc non-relativistic limit thisequation changcs to:
mm-2
whoro mx is thc mass of produced moson, m p is theproton mass and is the exccss encrgy. Thc finitewidth of thc missing mass peak is caused hy limitcdexperimental precision of the moasurod momentaA,
, arid, thercfore, can he exprossod as:
(A (mm2) )2 =
2
6MM2+ (
/2tP2i) 2)
(3),5P2i
2 +
22mx + 2mx . e 2mx
2rn
+ 1572 )2 , (2)0 _ -s "a_isassa,,ss J0.52
0.53
0.54
0.55
0.56
missing mass (CeV/e 2)
Figurc 1 : Missing mass of the proton-proton Sys-tem mcasured for three different momonta abovo andone momentum hclow threshold for 1-1 meson produc-tion. Thc dotted lins indicates the kinematical miss-ing mass limit.
06040
20
6040
20
p, = 1 .985 GeV/c
L
= 0 .5 MeV
Ph = 1 .979 GeV/c
(below thresholti)
p,=1 .991 GeV/c
e= 2.6 MeV
m,=0.5473 (GeV/c2)4,
whoro i numoratos the thrcc components of thc mo-mentum vectors. Wo assume, that thc experimentaluncertainties of the momentum vectors (dp lz and21p2i) am all equal to some constant valuc dp . Thepartial derivatives in cq. 3 arc calculated hy differ-entiation of eq . 2 . Next, averaging (MM2 )) 2 overthe phase spass for thc outgoing protons causes c .g.that products 13'1 -1-12 disappear, and after some alge-hra ono ohtains:
(A (mm2 ) ) 2 =
4 ( + 1 ) 2 + 4 I 27nP mx . . (Ap) 2
(4)m
mpmx
Thc width of thc peak in the missing mass squaredspectrum is thus proportional to li:
A(MM2 ) a f
(5)
As shown in Fig . 2, this formula reproduces the en-ergy dependence of the width of the missing masspeak ohscrvcd in the pp --s . pprl measurement well.
* Institute of Physics, Jagdlonian University, 30-059Cracow, Poland
2
4
6excess energy tMeV1
Figure 2 : Width of thc missing mass peak as afunction of the excess enorgy. The solid line cor-responds to a fit using eq. 5 with the parametera = 390 v/M eV 3 .
1ooo
0
20
1200
49
The Reaction pd
ri(n» at COSY-11
H.-H. Adam*, A. Khoukaz*, T . Lister* for the COSY-11 collahoration
Previous investigations in Saclay [1,2] on the pd'He ri rcaction in thc near threshold region Icad totheorctical interpretations of the production meeha-nism likc double scattcring processes [3,4] . Such cal-culations of the total cross seetions at excess encrgiese. < 7 MeV are in good agrecment with the Saclaydata, hut underestimate thc cross scctions derivedby thc GEM collahoration as well as preliminary re-sults of the CELSIUS collahoration at higher ener-gies (e > 40 MeV) [5,6] . Since in thc intomediatoenergy region no data exist, it was proposed to studythe n-production in the pd soanering predominantlyat excess cnergies up to e-. = 40 MeV.First measurements on the r7- and n°-production at
= 10 MeV and 40 MeV ~vcrc performed using theCOSY-11 detcotion system.COSY-11 is an infernal experiment, utilizing a set oftwo drift ohambers and two scintillation walls for thcidentification of positively charged particles and theprecise reconstruction of their four-momenta. The'He-nuclci are separated from Background-particles(n+ , p, d and t) hy their high energy loss in the scin-tillators . Undetoetui partielos are identified via themissing mass method and thus there exists a non-negligihle hackground from multi-pion production.
350
300
250
200
150
1
50
00.56
eV/c2 3
Figure
Missing m; is distribution for the rcactionpd
3 He at an excess energy of e = 10 MeV.
The resulting missing mass distribution for the pd3 He X reaction at e --s-- 10 MeV for t-production isshown in figure 1 . There is a dem peak in the regionof the mass of the with a FWHM of itit, 6 MeV andan integrated n-production yield over hackgroundcontrihutions of 1 :1 within a 3o width of thc peak.This is in accordance with Monte Carlo simulations,assuming two pion production to he the only hack-
ground mechanistn.
0 .2
-0.8 -0.4 0 0.4 0.83He 00scm(0)
Figure 2 : Angular distribution of tim, 3 He nuclei inthe center of mass system.
The knowledge of the angular distribution is essen-tial . Therefore, Monte-Carlo simulations have beeilused to correct the date for the limited spatial accep-tance . Figure 2 shows the ratio of the 3 He angulardistribution of the simulations with the real data . Inagreement with results from [1] also at e. = 10 MeVthe dato, am consistent with pure S-wave scattering.These firnt results Show the excellent capability ofCOSY-11 for the detection of 'He . Further mea-surements on pd 'He 17 and n" are in preparation.
References:
[1] B. Mayer et ah, Phys . Rev. C 53 (1996) 2068
[2] J . Berger et al ., Phys . Rev. Lee . 61 (1988) 919
[ 3 ] K . Kilian, H . Nanu, AIP Conf. Prot. . No. 221(1990) 185
[4] G. Fiildt, C . Wilkin, Nun Phys . A 587 (1995)769
[5] M. Betigeri et ah, c-Print Archive : nucl-ex/9912006 (1999)
R. Bilger et al ., Acta Phys. Polon . B 27 (1996)2985
* Institut für Kernphysik, Westfälische Wilhelms-Universität Münster, 48149 Münster, Gerrnany
0.52 0.54
50
ency of the neck Reeonst ction
the COSY-11 Drift Chamber Signals
Piotr Kowina* and Pawel Moskalt for the C0SY-11 Col
In the COSY-11 experiment the trajectories of positivelycharged ejectiles, momentum analysed by the dipolemagnetie field, are measured using multiwire drift cbers [1].The efficiency of the track reconstruction from the driftcharnber signals is a cmeial factor for the deemilna-tion of absolute cross seetions of reactions under inves-tigation . Since COSY-l 1 studies reactions of the typepp -+ pp Mesons and pp -4 pYK+ with at least twooutgoing charged te °des, it is particularly im t t toknow the efficiency for the reconstruction of the tracks oftwo partides passing simultaneously through the detec-tors [21.Speeffically, the reconstruction algo has to evalu-ate which signal belongs to which track or to reject it asnoise The decision depends an the distance between ameasured crossing point and a hypothetical track . Thedistance is measured in units of the position resolutionof the drift chambers which typically amotmts to ad , =-
0 .03 em (standard deviation) and can be established fromthe data for each experimental ruft.
100.
90Gl Q GI aaaaa
80
.0
method 4
method 62
200
0 .02
0.04
0 .060'cjc [ CM
Figure 1 : Efficiency for the two track reconstruction as afunction of ad,.
Thus, is one of die parameters which must be de-fined to perform the track reconstruction . Figure 1 showsthe two track reconstruction efficiency as a function of
used for the reconstruction of simulated events . Inthis particular case pp -4 ppn' events were gener-
a
omentum of 3 .2A0 GeV/c (threshold at
*Institute of Physics, Silesian University, PolandInstitute of Physics, Jagellonian University, Poland
3 .208 GeV/c) . The hit points in the drift ehambers weresmeared out with o-gmul = 0.03 cm. Next, the datawere analysed for diff erent er de values as input for thereconstruction. The figure indicates t the efficiencyincreases rapidly at ad,. set 0 .012 cm and then saturates at
ae., 0.015 cm at a value of . tut 85%. On the otherhand, the cornputing time grows exponentially with in-creasing erde , as shown in Figure 2 . In .a ition, bothpictures compare two methods of reconstruction whichdiffer slightly in the criteria used for the decision of as-signrnent of a signal to the track.
0 .02
0.04
0 .06
GM [ CMFigure 2 : Real CPU time of reconstruction for 5x10 5events.
The performed analysis shows that when takinglarger than the real one, the reconstruction efficiency in-creases by only a few per cent but shnultaneously makes
it much more time Ions
g. For example, ad,, beingassumed twice its real value results in 2% more recon-structed events but increases the needed CPU time by afactor of six.
Referenees:
[11 S. Brauksiepe et ah, Nucl . Instr. & Meth. A 376(1996) 397
[21 P. Moskal et ah, Annual Report 1997, IKP,Forschungszentrum Jülich, Jül-3505 (1998) 43
70
60
50
40
51
Deuterium Recuperation for Cluster Targets at COSY
H.-H . Adam*, A. Khoukaz*, N . Lang*, T . Lister*, C. Quantmeier*, R . Santo*, W .Verhoeven*
For oxperimonts at COSY two duster targets haveheen huilt at the IKP of the University of Münsterand installed in the internal experiments COSY-11and ANKE in 1995 and 1999, respectively [1-3] . Dueto the special design they allow to provide dusterbeams of all gases exeeist helium as targets for scat-toring experiments . For studies an elementary mesonand hyperon production processes in the pp-, pn-and pd-scattering, hydrogen and deuterium gas is ofspecial intarnst as target material.
Different to hydrogen, deuterium gas is compara-tively expensive . Therefore, a recuperation systemwas huild in order to reduce the loss of D 2-gas to aminimum. This system was successfully testest at aduster target in Münster and installed at the COSYring in summer 1999.
Thc deuterium fiow in the elosed ohnla is depictcd infigurc 1 : Exhausted gas is colloctod from the pumpstages and cleaned hy a special molecular filter toeliminate oil from the forepump. Thc pre-cIcanedgas passes a metal-mernbranc compressor and entersa hydrogen-purifier with a pressure of ,s 14 bar . Atthis point the deuterium must he free of oxygen toavoid damaltes of thc catalytic driven purifier . Afterthis procedurc ultra high pure deuterium is availahleand can directly he supplied to the duster target In-stallation.
To provide high quality duster heams, stahle condi-tions in thc gas supply system am neccssary . There-fore, a remote gauge system has heen installed inorder to monitor hoth the pressure of the exhaustedgas hehind the forepump as well as thc final pressureof the compressed gas . Together with the informa-tion of the measured gas fiow through the nozzle onecm easily check the status of the deuterium recuper-
ation system.The firnt tost Operation of the recuperation system atCOSY was performed within a C0SY-11 heam timein summer 1999. During a tost interval of toll hoursa stahle duster heam was produced in comhinationwith a deuterium loss of lass than 5% . This loss isdas to the amount of clustered gas which passes thescattering chamher for heam-target interaction andtherefore is not pumped away at the duster source.Hefora starting thc recuperation mode, the vacuumsystem of the duster source including thc gas sonnes-tion of the corresponding forepump exhaust to the re-cuperation system has to he flushod with deuterium.By this, hydrogen from previous duster modes aswell as oxygen and nitrogen is eliminated, which isessential to provide stahle deuterium duster haaras.Therefore, for an cifediva use of the recuperationsystem it is evident to have Iongor periods (> twodays) of continous operation with deuterium.
References:
[1] H. Domhrowski, D . Grzonka, W . Hamsink, A.Khoukaz, T . Lister, R.Santo, Nucl . Phys. A 386(1997) 228
[2] S . Brauksiepe et al ., Nucl . Phys. A 376 (1996)397
[3] H.H. Adam, A . Khoukaz, N. Lang, T . Lister, C.Quantmeier, R. Santo, The Cluster Target forthe ANKE-Experiment at COSY, contrihutionto this Annual Report
* Institut für Kernphysik, Westfälische Wilhelms-Universität Münster, 48149 Münster, Germany
Fi
1 : Gas fiow in deuterium recuperation system.
52
Meson Production Close to Threshold
H. Machner and J . Haidenbauer
The advent of strongly focusing synchrotrons such asthe IUCF COOLER in Bloomington, CELSIUS in Upp-sala and COSY in Jülich marks a new area in the studyof meson production in the threshold region . Due to theirhigh quality beams experiments could be performed withunprecedented precision and at energies being just a fewMeV above the threshold . Indeed a remarkable wealth ofdata has emerged from the experiments at those sites overthe past 10 years or so . In the following we will concen-trate only on hadron induced reactions and ignore photonand electron induced reactions although also for these re-actions beautiful new data have recently been published.In other words we will concentrate on strong interac-tions and we will restrict the discussion to only pseu-doscalar mesons . First, the vector mesons have muchlarger widths compared to the pseudoscalar mesons . Thismakes their detection difficult on top of a lange physicalbackground of multi-pion production events . Secondly,there seems to be a general trend that the larger the massthe smaller the cross section, so that the generally heav-ier vector mesons have small production cross sections,making them much harder to investigate than the lightermesons . In Fig . 1 we give an overview of total cross sec-tions in pp interactions below 4 GeV beam momentum.
Open symbols denote older data taken from compi-lations [1, 2] and references given in [3] . The fall andcrossed symbols denote the new data (cf. Ref . [4] for ref-erences) . The largest cross section is of course the totalcross section . Around 800 MeV/c the elastic cross sec-tion begins to be smaller than the total cross section be-cause the pion threshold has opened there . The strongestpion-production channel in the threshold region is thepp rr +d reaction which accounts for most of the in-elasticity in that momentum range . At larger momentait is the pp -4 prtrr+ reaction which exhausts almost allinelastic cross section . The next threshold that opens isthe pp reaction (multi-pion production is not in-cluded in the Figure) . lt is interesting to note that crosssections have been measured down to 10- 7 mb which isa fraction of 5 x 10 -9 of the total cross section . Later wewill show the cross sections again on different scales inorder to make different physical effects visible.
The first threshold which opens in nucleon-nucleon(NN) scattering with increasing beam energy is ir 9 -
production followed very soon by r+ -production . Pionproduction exhausts all inelasticity in this momentumrange (see Fig . 1) and is therefore fundamental for un-derstanding the nucleon-nucleon interaction .
2
3
4
pbeam (Gel/1c)
Figure 1 : Cross sections for pp interactions as function of thebeam momentum. Shown are total and elastic scattering crosssections and the cross sections for light meson production.Open symbols indicate older measurements.
Indeed, the reaction pp
ppmm was also the firstone to be studied with the new facilities [5, 6] . The totalcross section is presented in Fig . 2 as function of e.the pion center of mass momentum divided by the pionmass . The new data from IUCF and Uppsala [5, 6, 9] areshown as solid circles, earlier data from Refs . [1, 2] asopen circles . The quality of the new data becomes clearwhen inspecting the error bars which are for the new datausually smaller than the dots . Before the advent of thesedata, no data below 820 MeV/c existed.
53
distributions are not isotropic dose to threshold [11].
The third pion production reaction is the pp -+ pn7r+reaction . Its excitation curve as function of the beam mo-mentum dose to the threshold is shown in Fig . 2 . Againthe quality of the new data is impressive when the er-ror Bars are compared with the order data . The excitationcurve seems to rise less steeply from threshold on than thepp dlr+ reaction . Only for the reaction pn 2p7r+new data were not available to us but are in these pro-ceedings [13].
lt is interesting to compare the date on various meson-production reactions dose to threshold for a commonkinematical variable, namely as a function of the dimen-sionless cm momentum of the meson, = prn* /mm, ,where p?z is the maximum possible meson momentum.Then it becomes evident that all the reactions with threeparticles in the final state can be reproduced by just a sim-ple Power law
0- (n)
c77P -
This is demonstrated in Fig . 3 where the data are com-pared with Eq. 1 using p = 3 .2 and the normalizationconstants given in Table 1.
Figure 2 : Total cross sections for the NN
NN7r in thedifferent Charge channels . The meaning of the data symbols isas in previous figures. The date for the reaction np -4 pp1r-are taken from the compilation in Ref. [7] . The solid curvesshow the results of the Jülich model [8].
The differential cross sections are found to be inagreement with the assumption of isotropic pion emis-sion [6].
The new data for the reaction pp -+ pp7r° dose tothreshold raised a lot of theoretical questions, because thecross sections were much larger than theoretical predic-tions . New reaction mechanisms seemed to be necessaryin order to reproduce the data (cf ., e .g . the discussion inSect . 4.2 . in Ref . [4]) . On the experimental side it stim-ulated further research, namely to search in other pionproduction channels whether these new reaction mecha-nisms also contribute there . The hext reaction of interestis then the pp --+ d7r+ reaction . This is the pion pro-duetim which - together with its time-reversed reaction- has been studied most intensively . Surprisingly, doseto threshold no data existed before the advent of the newaccelerators . Total cross sections for the pp -4 dar + reac-tion are also shown in Fig . 2 . The new data from COSYand IUCF [10, 12] define the sharp rise of the cross sec-tions from the threshold on.
In contrast to the pp --+ pp7r 0 reaction, the angular
Table Normalization constant in Eq . 1 for differentreactions
reaction c (mbpp -+ pnrr+ 0 .7
PP -.4- pplr0 0 .1
PP -4 PP? 0 .2
PP -4 pp 7 ' 0 .04
pp
PAK+ 0.04pp -9- pE°K+ 0 .003
Surprisingly, the n' production and the associatedstrangeness production have the Same Cross section anthis seale . Even more surprising is the large constantfor production when eompared to 7r 0 produetim. Whenwe compare the following pairs of reactions, pn7r + andpp-1r°, ppr] and ppn', pAK + and pE°K+ , we see that ineach case the cross section of the first reaction is alwaysmuch larger than for the second . lt is certainly not aueidental that for each case it is always the first reactionwhich can proceed through an intermediate resonance(A, N*(1535) and N*(1650)).
54
lar phenomenon should be also visible in the strangenesschannel as was argued earlier. Thus, more probably theobserved enhancement dose to threshold is a hint for astrong hN FSI . The co an exponent may have its mainorigin in the common phase space of the three body finalstate with almost similar FSI between the baryons . Theexact values of the constants c depend, of course, on the riinterval where the curves were matched to the data . Thus,we want to stress that the values given in Table 1 are notobtained by a x 2 fit, but by matching the curves to thedata "guided by the eye" . The numbers are only meant togive an impression on an order-of-magnitudelevel.
References
[1] V. Flamino et a1 ., Compilation of Cross-Sections IH:p and Induced Reactions, CERN-HERA Report84-1, 1984.
[2] A. Baldini, et ah, Landolt-Börnstein New SeriesI/1 2b (Springer Verlag, Heidelberg, 1988).
[3] H. Machner, Nucl . Phys. A 633, 341 (1998).
[4] H. Machner and J . Haidenbauer, J. Phys. G 25,R231 (1999).
[5] H.O. Meyer et al ., Phys . Rev. Lett . 65, 2846 (1990).
[6] H.O . Meyer et ah, Nucl . Phys . A 539, 633 (1992).
[7] Bachman M G et al ., Phys . Rev. C 52, 495 (1995).
[8] Hanhart C et ah, Phys . Lett . B 444, 25 (1998).
[9] A. Bondar et al ., Phys . Lex . B 356, 8 (1995).
[10] M. Drochneret ah, Phys . Rev. Lett . 77, 454 (1996).
[11] M. Drochneret al ., Mich Phys . A643, 55 (1998).
[12] P. Heimberg et al ., Phys. Rev. Lett. 77, 1012(1996).
[13] T . Johanson, priv. communication.
Simultaneous Pinn Production in p+d Reactions
The GEM Collaboration
Figure 3 .Cross sections for various pp -4 BBm reactionswith B and m indicating baryons and mesons, respectively arecompared with Eq . 1 employing the saure exponent p 3 .2.The data and the curves have been multiplied by the indicatedfaetors.
Among the reactions considered only the h produc-tion data show a significant deviation from the simplepower law dose to threshold . As a first guess, this en-hancement of the cross section may be attributed to the
S11 (1535) resonance excitation . However, then a simi-
The study of meson production on the deuteron is thefirst step towards an understanding of meson productionon nuclei and the related in-medium effects . In a first ap-proximation, the reaction can be assumed to be mainly anucleon-nucleon reaction with the second nucleon in thedeuteron being a mere spectator [1] . However, the strucknucleon has a Fermi motion and thus an effective mass.In addition rescattering on the spectator nucleon may takeplace . All these processes do not take place in reactionson the nucleon.
Here we will concentrate on rr produetim, i . e. the
reactions
p + d
3 11e + 7r 0 ,
(2)
p + d 3H + lt+ .
(3)
The underlying elementary processes for both reactionsare the p + n --+ d + 7r 0 and the p p d + h- + reac-tions . In both reactions excitation of the A(1232) reso-nances plag an important rote.
The experiments were performed at the external pro-ton beam of the COSY accelerator . Because of its storagemode, one can extract the beam by a stochastic method
55
in time periods over several seconds, thus avoiding pile-up as well as dead time. The beam was focused to thecentre of a target cell [2], containing liquid deuteriumwith dimensions 6 mm in diameter and thicknesses from2 to 6.5 mm in the different runs, respectively. Recoil-ing baryons were detected in an angular range in the Iah-oratory system between 30 to 250 rnrad by a high pu-rity germanium stack detector called the germanium wall[3] . Paxticks emitted into smaller angles were identifiedwith a magnetic spectrograph . This setup has full accep-tance for threshold measurements in the center of masssystem. Dato were taken at beam momenta ranging from750 Mev/c up to 1050 MeV/c in steps of 50 MeV/c, thuscovering the full range of the 2s-excitation.
Figure
Angular distributions for the recoiling nuclei fromthe two reactions . The presently obtained eross sections arecompared with previous dato for approximately the saure beamenergy ([4, 5, 6]), or deduced from pion absorption employingdetailed balance (Ref. [7] . For the dato from Rössle et al . [8]Charge syrnmetry is assumed.
The information deduced from the germanium wallare energy, emission direction = (0,0) and particietype . The energy information for a given exit channelcan be transformed into the emission angle in the cen-tre of mass system without making use of the additionalmeasured quantities . However, possible background cannot be subtracted by this method . Therefore, the miss-ing mass of the unobserved pion is extracted by makinguse of all measurements together with the knowledge ofthe initial state and applying conservation of momentum,energy, charge and baryon number.
The measured differential cross sections in the centreof mass system for pion production at a beam momentumof 850 MeV/c are shown in Fig . 1, together with earliermeasurements dose to that beam momentum . The an-gular distributions for both reactions show a backwardpeaking of the A = 3 nuclei which corresponds to a for-ward peaking of the pion . This is also found in the otherdato to which the present results are compared with . Theflat part seen in the range cos(0) 0 is not found inthe time-reversed and isospin-related dato from Källne
et al . [7] . lt is again this region for the 'He + 7r+ chan-nel where the dato from Ref. [5] do not agree with thepresent results . The enhancement is predicted by a two-step process [9, 10], where the resultant pion scatters anthe spectator nueleon . lt is obvious that none of the ear-lier measurements has the good statistics of the presentresults . We have fitted Legendre polynomials to the angu-lar distributions . Polynomials up to 4th order were foundnecessary to achieve reasonable x2 values . From suchfits total cross sections were extracted . For the presentlyanalyzed dato these results are shown in Fig . 2.
Figure 2 : Excitation function for the indicated reaction . Thepresent dato are compared with other dato . Also shown are theresults from fitting the Germond-Wilkin model to the Iowenergy dato (dashed curve) and predictions of theLocher-Weber model (solid curve).
Obviously, the present dato bridge the gap between thenear threshold region and the dato above the resonancemaximum. Also shown are two calculations . One is afit of the model parameters of the Germond-Wilkin [11]model to the Iow energy dato, which nicely accounts forthese dato. The solid curve is a calculations within theLocher-Weber model . Here no parameters were adjusted.This model works well only in the region of the resonancemaximum.
References
[1] M Ruderman, Phys . Rev . 87 (1952) 383.
[2] V. Jaeckle, K . Kilian, H . Machner, Ch . Nake, W.Oelert, P. Turek, Nucl . Instruments and Methods inPhysics Research A 349 (1994) 15.
[3] M. Betigeri et al ., Nuelear Instr . Methods in PhysicsResearch 421 (1999) 447.
[4] G. Lolas et ah, Nucl. Phys. A 386 (1982) 477.
[5] J . Carol et al ., Nucl . Phys . A 305 (1978) 502.
[6] J . M . Cameron et al ., Nucl . Phys . A 472 (1987) . 718
[7] J . Källne et al ., Phys . Rev . C 24 (1981) 1102.
0 .0
0.5
L5
2.0
2 .5
3 .0
56
[8] Dutty, Diploma thesis, Freiburg (1981), E.Rössle et ad ., Pion Production and Absorption inNuclei, R. D. Bent (ed .) AIP Conf. Proc . 79 (1982)171.
[9] K. Kilian and H . Nann, AIP Conf. Proc. No . 221(1990) 185 .
[10] M. P. Locher and H . 3 . Weber, Nucl . Phys . B76(1974) 400.
[11] LT. Germond and C . Wilkin, J . Phys . G 16 (1990)381.
'Production in the S 1 es
region
The GEM Collaboration
The production of ri mesons has recently attractedsome interest due to its large unexpected cross sec-tion in baryon induced reactions dose to threshold [1].Such large cross sections stimulated the developmentof models going beyond the Ruderman approach [2],.i .e. assuming the process to take place primarily as anucleon-nucleon interaction with the second nucleon inthe deuteron acting as a spectator . One of these modelsis the two step approach developed by Kilian et al . [3],assuming in a first nucleon-nucleon interaction a pion tobe produced which then in a second step interacts withthe spectator to produce the meson . GEM has studiedthe
p+d-+
(4)
reaction at a beam momentum of 1673 MeV/c . In Fig . 1the results
Figure 1 :Angular distribution of the reactionp + d -+ 3He + 77 . Added are two points from Ref's [4, 5] . ALegendre polynomial fit is shown as solid curve.
for the production are shown . Results from two differ-ent runs agree nicely with each other . Two data pointsfor backward emission from Ref .'s [4, 5] are added . Thetotal cross section is extracted from a second order Leg-endre polynomial fit, also shown in the Figure . lt shouldbe mentioned that this measurement is still subthresholdin the nucleon-nucleon system, although Tüte far abovethe absolute threshold . The large momentum transfer of
Ap 706 MeV/c, which is nearly double than in thepion reaction, corresponds to a distance of only 0 .27 fm.The reaction is, therefore, extremely sensitive to the highmomentum components in the deuteron wave function.
The present angular distribution shows a strong for-ward peaking for the meson, similar to the angular distri-butions in pion production (see previous contribution inthis report) . The distribution is almost isotropic dose tothreshold . The deduced total cross section is comparedwith previous measurements in Fig . 2 . lt is dose to theprevious result from Banaigs et al . [4] . The energy regionfrom 900-1100 MeV corresponds to the centre of the N*Sti resonance (F 200 MeV) known to couple stronglyto the rt-N channel [7] . One may therefore attempt todescribe the cross section by an intermediate N*(1535)resonance excitation . The cross section is calculated as
a(E) 132 M(E)i 2pp
with E the excitation energy and M the matrix element.All momenta p are in the centre of mass system. This iscalculated as in photoproduction an the proton [6]
AF2M(E)I2 R (6)(E
r ) 2 + F(E) 2
with
r(E) =
,7 P'q +b, P7r +b,,Pn,R
,R
Similar to Ref. [6], we applied a width at the resonanceof FR=200 MeV, a Breit-Wigner mass of m R in-1540MeV/c 2 . The branching ratios were set to 6, 7 =0.47 forthe decay, b,=0 .48 for the pion decay and b, ,=0 .05 forthe two pion decay [7] . The momenta at the resonanceposition are indicated by the index R . The only free pa-rameter is the strength A taken to be 241 nb in order to fitto the present data point . The predictions of this modelare also shown in Fig . 2 .
(5)
(7)
57
Figure 2 :Excitation functions for production in variousreactions . The present result is shown as large square witherror bar. Solid curves are calculations with the modeldiscussed in the text for excitations of the N* (1535)resonance . The dashed curve is the the model eaIculation lautfor a resonance IV* (1740).
lt reproduces the trend of the data except for very smallenergies . The Zarge cross sections there may be a sign ofstrong final state interactions (FSI) between the and the3He . This is surprising since one expects the formfac-tor given by the overlap of the deuteron and 'He wave-functions to show also an energy dependence as does theelementary eross section. In order to study this effectfurther we compare cross section data for the reactionir - p n with this model, fitting again only the ab-solute height . This comparison is also shown in Fig . 2.Again the agreement between data and caIculation is re-markable although the bumps in the experimental exci-tation function was attributed to higher N* resonances[8] . The same energy dependence of the matrix elementswhich is given by the excitation of the N*(1535) reso-
nance hints to a dominant production mechanism via in-termediate ir exchange with N* excitation.
We then proceed and compare data for the pp 77 2preaction with the present resonance model . This is donein Fig . 2 for data which are corrected for FSI betweenthe two protons . The agreement between data and cal-culation is less satisfactory than for the other reactions.Again an excess in cross section is visible dose to thresh-old pointing again to a strong FSI between the and thetwo protons . The additional rise of the cross sectionsabove = 0 .3 can not be accounted for by the presentresonance model . However, if one assumes another N*resonance to exist one can apply the same model yieldingalmost the same width and a Breit Wigner mass of 1740MeV/c 2 . This behaviour in the different excitation func-tion deserves further investigations including polarizationobservables.
Referenees
[1] B . Mayer et al ., Phys . Rev . C 53 (1996) 2068.
[2] M Ruderuran, Phys . Rev . 87 (1952) 383.
[3] K. Kilian and H . Nann, AIP Conf. Proc . No. 221(1990).
[4] J . Banaigs et al ., Phys . Lett. 45B (1973) 394.
[5] P. Berthet et al ., Nucl . Phys . A443 (1985) 589.
[6] B . Krusche, Acta Phys . Polonica 27B (1996) 3147.
[7] Particle Datei Group : C. Caso et al., The EuropeanPhys . 3 . 3 (1999) 1.
[8] J . M. Laget et al ., Phys . Rev. Lett . 61 (1988) 2069185.
Test measurement of isospin symmetry breaking in the p+d'H+7r+ andp+d> 3 rle+7r0 reactions
The GEM Collaboration
Experiments searching for the Marge symmetrybreaking effects were proposed in our original pro-posal [1], where a detailed motivation for such a studywas given. lt was stated that the energy dependenceof the cross sections ratio for the p+ds--OH-err + andp+d--4 3 1le+Ir 0 reactions at the beam momentum dose to1 .57 GeV/c should be measured . Basic subject of this in-vestigation is the isospin symmetry breaking due to n.0-nmesons mixing . The beam momentum was chosen tobe dose to the meson production threshold, and the"HI'He cross sections ratio should be measured at largerelative angles of incident proton and outgoing pion . Un-der such conditions the amplitudes for 17 and rr° produc-
tion are comparable, giving substantial contributions tothe isospin symmetry breaking . The proposed method ofdetermining the energy dependence of the ratio of crosssections is based an simultaneous detection of 3 H and3 He. lt is therefore to a large extent immune to Problemsof relative normalization (luminosity variations) and thusensures high accuracy of the results, allowing to studyeven quite small effects of the isospin symmetry break-ing .
In order to fulfil those strict requirements it was pro-posed to use the Big Karl spectrometer . lt allows the mo-mentum separation of the beam and reaction products,enabling the measurements at luge proton-pion relative
58
angles, reaching 1800 in the can . system. Simultaneousdetection of 3He and 3 H will be achieved by deteefing he-lium at the focal plane and tritons at the first dipoleyoke hole. For this purpose the new detection setup con-sisting of two sets of drift ehambers and two layers of thescintillator hodoscope was mounted at the Big Karl firstdipole yoke hole. The performance of this detection sys-tem was tested and it was shown that even in the presenceof a large background produced in the neighbouring beamdump region the detectors operated very well . The de-tailed deseription of this new detection system was givenin Ref . [2] . The first test run allowed almost backgroundfree identification of the p+d--a- 3 He+Ir° reaction by reg-istering 3 He at the focal plane detection system [3] . Alarge trigger rate was observed in the detection systemlocated at the first dipole yoke hole . In order to reducethis trigger rate various methods were applied . A newsmall magnet was mounted upstream from the target . ltallows to change the horizontal beam incidence angle onthe target, shifting therefore the beam dump away fromthe position dose to the dipole yoke hole detection sys-tem. Additionally the first level correlation trigger wasapplied . lt correlates appropriate scintillator paddles intwo hodoscope layers placed about 3 meters apart . Thedetails of the improvements leading to background andfalse trigger rate reduction in the dipole yoke hole detec-tion system are given in ref. [4] . The applied methodsled to the trigger rate reduction by a factor of about 150,what would be soffteiern to perform the planned measure-ments at the full beam intensity with the acceptable deadtime . Further planned improvements in the detector sys-tem (see [4]) will lower the dead time to a level below10%. The first measurement of the p+d--3.3 1-1+tr + reac-tion was carried out and its almost background free iden-tification was observed . The resulting time of flight spec-trum with the peak corresponding to 3 H produced in thisreaction is shown in Fig . 1.
In the test measurements it was shown that theplanned experiment is feasible . At the planned operat-ing conditions the expected counting rate is about 74 perhour for 3 He and about 11 per hour for 3 H. The aboverates, estimated on the basis of the cross sections valuesand the expected luminosity are fully supported by therates measured in the test experiments . Since in the rel-ative measurements most of the systematic errors cancelthe accuracy of the 3 H1 3 He cross section ratio is limitedby the statistical error only . The achieved backgroundreduction results in the almost background free spectra,
therefore the accuracy of the experiment is defined by thestatistieal error only. The expected counting rate wouldallow to reach the accuracy of the cross sections ratio ofabout 2% within one week run, what should be comparedwith the expected 10% variation due to the isospin sym-metry breaking.
Z-00
03
2
>1. ,
2
16
18
20
22
24TIME OF FLICHT (-,s)
Figure 1 : Time of flight spectrum measured with the firstdipole yoke hole detection system. The 3 H peak is markedwith the Gaussian curve, for which the position and width weredetermined on the basis of the deuteron events, analyzed in acompletely analogous way as the triton olles.
References
[1] A. Magiera, COSY Proposal No . 59 (1997).
[2] GEM Collaboration, Annual Report 1998, KFA-IKP, 1999, p . 28.
[3] GEM Collaboration, Annual Report 1998, KFA-IKP, 1999, p . 30.
[4] GEM Collaboration, Background reduction meth-ods for Big Karl first dipole yoke hole detection sys-tem, contribution to this Annual Report.
59
Backgmund reduction ethods for Big Karl first dipole yoke
detection
system
The GEM Collaboration
A new deteetion system at the Big Karl first dipoleyoke hole was mounted and tested [1] . The main goal ofusing the detection system at this place is the measure-ment of the isospin symmetry breaking in p+d--OFI-I-rr+and p+d--->3 He+7r 0 reactions (see refs . [2] and [3] for de-tails) . In the performed test measurements it was foundthat large background and consequently large trigger ratelimit the acceptable counting rate at this new detectionsystem. In order to reduce the background and the falletrigger rate the Big Karl was equipped with the systemallowing to change the horizontal beam incidence angleon the target.
Figure Trigger counting rate in the detection systemlocated at the first dipole yoke hole as the function of thehorizontal beam incidence angle on the target.
Additionally the correlation trigger for the dipole yokehole detection system was applied . Observed in thedipole yoke hole deteetors high background was causedby beam scattering on the wall of the dipole vacuumchamber and by the beam dump located close to these de-tectors . In order to reduce this background an additionalsteerer windings on the beam line quadrupoles (Q48Aand Q49A) and a small dipole magnet about 50 cm up-stream from the target were mounted . This system al-lows to change the horizontal beam incidence angle onthe target by up to about 20 mrad . The beam angle wascontrolled with the standard MWPC deteetors for beammonitoring and with the viewer mounted at the target po-
sition . Small change in the horizontal beam incidenceangle on the target causes a large shift of the positionwhere the beam hits the vacuum chamber wall as wellas of the beam dump position at the first dipole . This al-lows to reduce the background in the detector system lo-cated dose to the beam dump and provides enough spaceto add passive shielding . The background suppression asthe fülletim of the beam incidence angle on the targetwas measured and the result is shown in Fig . 1 . lt wasfound that the background reduction by about factor of 10may be achieved with the beam incidence angle of about10 mrad, while for larger angles the background remainsconstant . lt is due to the scattering and production of sec-ondary particles at the position were the beam exits thedipole magnet material.
--'-N
Figure 2 : Schematic view of the final detection system at theBig Karl first dipole yoke hole.
Further background reduction by a factor of 4 wasachieved by mounting a provisional lead wall betweenposition of the beam exit from the dipole and the detec-tion system . Employing all these modifications resultedin lowering of the single counting rate in the detectionsystem, thus reducing very strongly random coincidenceslevel - by a factor of about 200 . This in turn greatly im-proved the tack reconstruetion in the drift chambers, in-creasing the event identification efficiency . The triggerreduction was achieved by mounting veto counters, cov-ering the side of the lead wall and by the use of the mod-ified scintillation hodoscope layer. This new hodoscopelayer consists of shorter, thicker and narrower scintillatorpaddles, allowing better particle identification and man-struction of first level correlation trigger. This triggercorrelates appropriate scintillator paddles in the two ho-doscope layers located about 3 meters apart . lt allows totrigger the acquisition only on events coming through thedipole yoke hole, eliminating therefore all the particlescoming from the beam dump, located on the side of the
60
hole . Application of the correlation trigger lowered thetrigger rate by the a factor of about 4 . In the next stepalso the second layer of the hodoscope will be replacedby thicker (and possibly narrower) scintillator paddies, toimprove the particle identification . The passive shield-ing will be optimized and positioned in a way to fullyexploit its advantages. Final detector set-up that will beused for particle detection at the first dipole yoke hole isshown in Fig . 2 . All the up to now applied methods ofthe background reduction and improvements in the trig-ger logic resulted in decreasing of the trigger rate by afactor of about 150, what would be sufficient to performthe planned measurements at the full beam intensity withthe acceptable dead time . In the final configuration a fur-ther decrease of the trigger rate will push the dead time to
a level below 10%.
References
[1] GEM Collaboration, Annual Report 1998, KFA-IKP, 1999, p . 28.
[2] GEM Collaboration, Annual Report 1998, KFA-IKP, 1999, p . 30.
[3] GEM Collaboration, Test measurernent of isospinsymmetry breaking in the p+d-+ 3 Haeir+ andp+d-+ 3 He+ir° reactions, contribution to this An-nual Report.
61
The EDDA Experiment : Excitation Fundions of Proton-Proton Scattering at
Intermediate Energies
J. Bisplinghoff, F . Hinterberger and
Scabel for
the EDDA collaboration [1]
1 Motivation and General Description
The EDDA experiment [2] is designed to providea high preeision measurement of proton-protonelastic scattering excitation functions rangingfrom 0 .5 to 2 .5 GeV of laboratory kinetic energy,Tp. lt utilizes the proton beam of the coolersynchrotron COSY [3] operated byForschungszentrum Jülich . The proton-protonelastic scattering [4] is fundamental to the
understanding of the strong interaction . Excitationfunctions for cross sections and polarizationobservables of the pp interaction, in particular theelastic channel, provide the data base for phaseshift analyses serving as input to calculationsconceming nuclei and the test of meson exchangemodels [5] . The experimental dato base is ratherpoor [6] for energies Tp >1 .2 GeV and there is aneed for exclusive data in narrow energyincrements and over a large angular range . Suchdate are also suitable to either detect dibaryonicresonances or to plane upper 1imits an theirexistence in case of their coupling to the elasticchannel.
Figure 1 : The EDDA detector and 1 e atomic beam target s seen fram downstreai
62
.g
-1-'i
The measurement of analyzing power (AN) andspin correlation coefficients (here : ANN , Ass, As')requires a polarized COSY beam and a polarizedEDDA target . EDDA was conceived as anexperiment using the intemal recirculating COSYbeam in order to obtain Imninosities high enoughfor use of a polarized atomic beam target [2].Data collection proceeds during synchrotronacceleration in a multipass technique, so that afüll excitation funetion is measured in eachacceleration cycle . Statistical accuracy is obtainedby averaging over many cycles. is techniquerequires (and has demonstrated) a very stable andreproducable Operation of COSY.
The EDDA detector (Fig .l) was designed forlarge solid angle coverage in a cylindricalgeometry . Elastic events are identified bycoplanarity with the beam (2 1 - 2 2 = 180» andthe elastic scattering kinematics, which imposetan 0 1 , bb ° tan 0 2jab = 2 mpe2/(2mp.c 2+Tp ) . Theseconditions are employed with different degreesof stringency both in triggering and in eventidentification during offline analysis . The EDDAdetector consists of two cylindrical double layerscovering 30° to 150° in for the elastic ppcharmel and about 85 % of the fall solid angle.The inner layers are composed of scintillatingfibers which are helically wound in opposingdirections They are not required and were notinstalled when measuring spin-averaged crosssections with a CH 2 fiber target, but are essentialfor vertex reconstruction when measuring spinobservables with the polarized atomic beamtarget. The outer layers consists of 32 partlyoverlapping scintillator bars which are ingparallel to the beam axis and which are read out atboth ends. They are surrounded by scintillatorsemirings . Analysis of the fractional light outputis used to deterrnine the angles of incidence muchmore accurately (by a factor of 5) than would bepossible on the basis of detector granularity alone.Combined with the spatial resolution of the 2 .5mm scintillator fibers this provides for vertexreconstmetion to a precision of about 2 mm(FWHM). Details are given in Refs .[2,7 ].
2 Status and Recent Progress
Taking unpolarized data with outer detector layeralone using CH2 fiber targets and C fiber targetsfor background subtraction was completed in1996, and ferst cross sections resulting from thedata published [8] . Meanwhile the whole set of
data is analyzed (Fig .2). During the run inNovember 1997, emnrnissioning of the innerdetector layer and of the polarized atomic beamtarget [9] was completed as scheduled . Thepolarized hydrogen atoms are prepared using anatomic abeam source with dissociator coolednozzle, permanent sextupole magnets, and RFtransition units . In the beam dump thepolarization is continuously monitored using aBreit-Rabi polarimeter . A peak polarization ofabout 85% with an effective target density of 2.10 11 atoms/cm 2 has been obtained; taking theunpolarized hydrogen backgromd in the targetregion into account the effective polarizationamounts to about 60% . The FWHM diameter atthe target point is about 12 mm.
10
Figure 2 : Excitation functionsfor L7,,,, = 57°G =1 ° and73° dir it. p = 25 MeV/c hins. The solid curve is theSAID solution SP99 containing the fractional EDDAdata set of Ref 28L7
Three runs in 1998 and 1999 were devoted almostexclusively to the collection of analyzing powerdata using the unpolaized COSY beam and thepolarized atomic beam target. With 1 .5 ° 106turnsls and 3 - l0 1ß protons in the ring aluminosity of 7 lo'/cm2s was achieved . Datawere taken during acceleration and deelaration ofthe COSY beam. The time period of one cyclewas about 13 s . The direction of the targetpolarization was changed from cycle to cyclebetween ±x and ±y thus allowing a proper spinflip correction of false asyrnmetries [10] . Sincethe target polarization is constant during anacceleration/declaration cycle the analyzingpower excitation fimction can be measured with ahigh relative accuracy . The absolute calibration isestablished with reference to angular distributionsmeasured at Los Alamos near 1400 MeV/c with ahigh absolute accuracy [11] .Some preliminaryresults are shown in Fig. 3. Impact on the spin
19001006 2006
p (1V1eVle)
63
triplet scattering phases is expected [12] from acomparison with the SA1D solution SP 99 . Nowpreparations for measuring excitation functions ofpolarization con-elation observables A, Ass andASLare underway.
Figure 3 : PRELIlvIINARY experimental excitationfunctions A N(pp) . Elastic scattering data are for /I7 m
6° and ./1p, = 30 MeV/c hins. The SAID solution SP99is shown as solid line.
The EDDA collaboration wishes to acknowledgethe great support it has been receiving from theCOSY team.
References
[1] The EDDA collaboration : M. Altmeier ' , F.Bauer2 , J . Bisplinghoff, M . Busch ' K. Büßer 2 T.Colberg2 , L. Demirörs2 , O.Diehl ' F. Dohrmann2H.P . Engelhardt ' , P.D. Eversheim ' ,O. Eyser2 , O.Felden ' , R. Gebe1 3, M. Glende', J Greiff2, R.Groß-Harde F Hinterberger' , R. Jahre, E Jonas2 ,H. Krause2 , R Langkau 2, T. Linde a 2 , J.Lindlein 2, R. Maier3, R. Maschuw' , A.Meinerzhagen ' , O. Nähle ', D Prasuhn3, H.Rohdjeß ', D. Rosendaal ' , P . von Rossen3 , N.Schirm2 , V. Schwarz ' , W. Scobel 2 , H.J . Trelle ' , E.Weise ' , A. Wellinghausen2, K. Woller2, R.Ziegler ' ,
(1) Inst . für Strahlen- und Kernphysik, Univ.Bonn,
(2) I . Inst. für Experimentalphysik, Univ.Hamburg.
(3) Inst . f. Kernphysik, FZ Jülich.
[2]J. Bisplinghoff, and F . Hinterberger, ParticleProduction Near Threshold, MP ConfProc . 221,312 (1991) ; W. Scobel, Phys. Ser. 48, 92 (1993);H. Rohdjeß, Proc. Int. Conf On Physics withGeV-Particle Beams, Jülich, 1994 Singapore:World Scinetific, 1995, p. 334.
[3]R. Maier, Nucl. Instr. And Meth . In Phys . Res.A 390, 1 (1997).
[4] C. Lechanoine-Leluc, and F . Lehar, Rev Mod.Phys . 65, 47 (1993).
[5] R. Machleidt, Adv. in Nucl. Phys . 19, 189(1989).
[6] R. A. Arndt, et ah, Phys . Rev. C 56, 3005(1997), SAH) solution SM97.
[7] M. Alteneier et al, Nucl. Inst. Meth in Phys.Res. A431 (1999) 428
[8] D. Albers, et al . Phys . Rev Lett . 78, 1652(1997).
[9] P .D. Eversheim, Nucl . Phys. A626,117c(1996).
[10] G.G. Olsen and P .W. Keaton, Jr ., Nucl. Instr.And Meth . 109, 41 (1973).
[11] M.W. Mc Naughton et al, Phys . Rev . C41(1990) 2809
[12] W. Scobel et al, Proc. STORI 99 (Edts: H.O.Meyer arid P. Schwandt)MP (2000)
The Storage Cell Ihr the EDDA-Experiment at COSY
M. Glende, P .D. Eversheim, O. Felden, R. Gebet, the EDDA-coliaboration
To obtain a higher luminosity a storage cell hasbeen implemented at the EDDA-experiment [1] andferst tests have been conducted . The effective targetthickness of the cell depends an its geometry andtemperature . The cell [3] is build with an apertureof 12x29 mm2 and a length of 300 mm. lt isfastened to a cold head for wohlig it down to atemperature of 100 K. Lower temperatures can beachieved but decreas the polarization of the targetgas. The feeding tube with a length 100 mm isconically shaped according to the atomic beamprofile . An elastic r i amp ensures a sufficient heatconductance (Fi g . 11.
Fig. 1:The storage cell with the feeding trabe. Anelastic ciamp ensures a sufficient heatconductance as the feeding tube is cooied by thecell.
With an intensity of the atomic beam of 2 .8°1016 /s
[4] a target thickness of 8.5°10 12 atoms/cm 2 isexpected in the cell.In Erst runs of the EDDA-detector with the storage
cell a high background scattering rate was observedbecause the halo of the COSY-beam hits the cellwalls especially at the end of the cell . This can beseen in Fig. 2 where the counting rate with andwithout target gas is shovvn along the beam axis ofthe storage cell . The counts in this figure arefiltered for elastic p-p scattering . From that data adensity profile of the target gas in the cell wasderived which is in good accordance with theprofile calculated by Monte-Carlo simulations(Fig .3).Due to the high background scattering rate theCOSY-beam intensity had been redwed to
1 .2-10 16 p/s . With this intensity the luminosity iscaiculated using by the counting rate of the detectorfor p-p elastic scattering and the total cross section,
giving a value of 3.8°10 27 /(s° cm». This isreasonably close to the expected luminosity of
7 . 1o 27 /(s-cm2) taking into account the uncertaintiesabout the intensity of the COSY beam, the atomicbeam density, and the focusing in the target cellduring the test ruh . With the anticipated reductionof beam halo it is expected that at an intensity of10 10 partiele in the ring a luminosity of7 i o 28/(s-cm') is obtained.
References:[1] J . Bisplinghoff & F . Hinterberger, AIP Conf.
Proc ., 221, 312 (1991)[2] P .D. Eversheim, Huch Phys . A626 (1997) 117c[3] M. Glende, An. Rep. 98, p 45[4] M. Altmeier, Ph .D. thesis 1998
Fig. 2:Counting rate of detected events along the storagecell . The cell extends from -150 mm to +150 mmin the direction of the COSY-beam. At the end ofthe cell the halo of the COSY-beam hits the cellwall . The bin width is 2 mm in beam direction .
Fig.Counting rate of detected elastic p-p events along thestorage cell derived from Fig . 2.The detector eheloses only the downstream half of the cellbetween 0 mm and +150 mm . In this part the counts agreewith the density profile caIculated with Monte-Carlo-simulations . In the upstream half of the cell the counts arelimited by the acceptance of the deteetor.
65
Results on Twa - Kahn Produetim at MOM0
F. Bellemann ' , A. Berg ' , J . Bisplinghoff' , G .Bohlscheid ' , 3 . Ernst, F. Hinterberger ' , R. Ibald ' ,R. 3ahn1 , L. Jarczyk2, R. Joosten ' , A. Kozela 3 , H. Machner, A . Magiera2, R. Maschuw' ,
T. Mayer-Kuckuk l , G. Mertler' , J .Munkel l , P . v . Neumann-Cose14 , D. Rosendaal ' , P . v . Rossen,H. Schnitker ' , 3 . Smyrski2 , A. Strzalkowski2 , R . Töne, and C . Wilkin5
The MOMO experiment focuses on near thresholdmeson production via the reaction pd 3He 7t÷rc- andpd es.> 3He K+ K lt takes advantage of the high qualityof the cooled external COSY beam and the existingspectrometer BIG KARL . The setup consists of a highgranularity scintillating fibers meson detector near thetarget with a ± 45 deg . opening angle, and the spectro-meter, which is used for 3 11e-identification. The largesolid angle and high resolution of this detection methodwill yield precision data on the Iow energy (T<80 MeV)meson-meson interaction and probe into questions Ilkemeson-nucleon resonances and KK-molecule.
The MOMO vertex detector consists of 672 scintillatingfibers (round, 2 .5 diameter) arranged in three planestilted 60 deg. versus each other . Each plane issubdivided into two identical rnodules . The fibers areread out by 16-fold photomultipliers . The totalefficiency was measured to be better than 99% forminimal ionizing müdes . The BIG KARLspectrometer is also fully operational . Its status isdescribed in detail elsewhere in this annual report . TheMOMO scattering chamber houses the 4rnm LD2 targetas well as a remotely steerable ladder for beam viewersand solid targets . The 5 mm thin Al front end of thechamber faces the vertex detector on the outside andkeeps straggling of the mesons at a small level.
Until 1997, the MOMO collaboration measured the pd-4 3 He tr+rC reaction at three different proton beammomenta (1060 MeV/c, 1150 MeV/c, 1200 MeV/c),corresponding to 28 MeV, 70 MeV and 92 MeV centerof mass energy above the reaction threshold . In total,some 30 000 kinematically complete rc +r( - events wereobserved . The obtained two pion invariant massspectra showed a strong deviation from phase space atall three energies, whereas the lt - 3He missing massspectra followed phase space. The pion angulardistributions displayed a remarkable sidewise peaking(in the c .m .s .) and a preferential back to back emissionof the two pions . This behaviour can be well describedby calculations assuming a p-wave between the twopions and s - waves in the - 3 He system.
In 1998 and 1999 the MOMO collaboration measuredtwo kaon production via the reaction pd -4 3He K+ K - atbeam momenta of 2.585 GeV/c and 2 .620 GeV/c (Q40 MeV and 56 MeV, respectively) . The beam intensitywas about 10 9/s with a cycle of 12 s beam on and 8 sbeam off. Furthermore, for the first time the beam halowas negligible (< 10-4) . The count rate of the newlyimplemented halo veto counter was only some 80 K/s .
At Q = 56 MeV the reaction pd 3 He K + K - wasmeasured at four largely overlapping BIG KARLmomentum settings, so that the fall phase space of thereaction was obtained . The 3 He partieles could beunambiguously identified by time of flight and energyloss measurements. The two -kaon hits on the vertexwall were uniquely identified by their hit pattems andenergy loss . Good events must be coplanar in respect tothe total meson momentum axis, which is defined by thebeam and the 3He momenta. The newly implemented 16
fold circular scintillator hodoscope behind the vertexdetector enables good kaon identification and pionseparation. In total, some 3000 two kaon events wereobserved. The (still preliminary) results of our dataanalysis are displayed in the figures.
Pre«rnIrtary
e 22_5
1- 20
b
'0 17,3
10 1
20
30
30 3
T..,3- MeV 3
Fig. 1 : K+ K - invariant mass spectrum from the reactionpd 3He K + IC at 56 MeV above reaction thresholdplotted in units of K+ K i relative energy . See text.
Fig .I shows the obtained two kaon invariant massspectrum. A clear signal of the phi meson is evident.Fig . 2 and fig . 3 show the kaon angular distributionsand fig .4 the kaon - helium invariant mass spectrum . Inall figures, the dashed lines correspond to phase space.In contrast to our two pion data, no significant deviationfrom phase space (plus phi - production) can beobserved. The bump in the relative angle spectrum(fig .3) originates from kaons arising from phi - decay,since these events are limited to a maximal possiblerelative angle deternüned by reaction kinematics.
66
Fig . 5 Shows firnt data at Q = 40 MeV . Here only about50% of the fall Phase space have been measured so far.A clear signal of the phi meson is evident, here 8 MeVabove the phi production threshold . Data analysis is ingood progress arid further measurements of this reactionat different beam energies near threshold will beinteresting.
CO5
Mg 2: Angular distributions of the individual kaons inthe c .m.s . at 56 MeV above threshold . See text.
-0 .6
-0.2
0
0,2
0 .4
0.6
0 .6a0s(te)
Fig. Distribution of the relative angles between thetwo kaons in the c .m.s . . See text .
Prelitninary
30
50-r-
Fi . K - 3He invariant mass spectrurn from thereaction pd 3He K+ K at 56 MeV above reactionthreshold plotted in units of K 3 He relative energy . Seetext .
10
20
30
.
0
14 _ Pre,Ilrnlncry
2
Fig.5 : K+ K - invariant mass spectrum from the reactionpd 3He K + K - at 40 MeV above reaction thresholdplotted in units of K + K - relative energy . See text.
Institut für Strahlen- und Kernphysik, UniversitätBonn
2 Institute of Physics, Jagenordan University, Cracow,Poland
3 Institute of Nuclear Physics, Cracow, Poland4 lnstitut für Kernphysik, Technische Universität
Darmstadt5 Physics & Astronomy Department, University CollegeLondon, UK
0.2
0
0.2
0.4
0 .6
023
P e05..5.5no,e,
2 .5 E
2
12.5
2 .2
2 .5
.2
12 -
10
50
6T5,,- [MeV 1
67
68
70
Status of the ATRAP - Experiment at the AD/CERN
Bojowald, J . But, W. Erven, H.-W. Firmenich, D . Grzonka, H . Hadamek, M . Holona, H . Jansen, M. Köhler,M. Kremer, M . Küven, R. Neilen, W. ()eiert, G . Schepers, J . Schmitz, F. Schultheiß, Sefzick, D. Spölgen, J. Strehl,
P. Wüstner, K . Zwoll
The ATRAP [1] collaboration focuses its attention to thegreat challenge of comparing hydrogen and antihydrogento high accuracy . The current assumption, that reality isinvariant under CPT transformations, is based in Zargepart upon the success of quantum field theories, whichthemselves rely an reasonable presumptions as causal-ity, locality and Lorentz invariance. Theoretical inves-tigations of possible CPT violations are now beginningto appear in the context of string theory [2].The year 1999 was used by the different collaborationpartners to produce the part which they were supposedto deliver for the common experiment . Here we give ashort summary, the ATRAP experiment is descibed eise-where [3] : The accelerator team of the AD managed todecelerate 106 - antiprotons down to 100 MeV/cmomentum . Due to the Lack of electron cooling at thisearly stage the dimensions of the extraeted beam were9 x 10 mm 2 and not 4 x 4 mrn 2 as foreseen . The su-perconducting magnet was running at a central field of6 Tesla . The trap itseif was cooled down to liquid Hetemperature and succeeded to trap electrons as a proof ofits faultless operation . The PPAC detector (a thin pro-portional chamber) registered the burst of antiprotons in-jected into our apparatus simultaneously to the signalsfrom the scintillation detector surrounding the magnet.The Positron source was installed after the shut-down ofthe accelerator complex at CERN.
Figure 1 : D . Spölgen and J . Strehl mounting the fiberscintillators.
The Part of the Jülich team was to incorporate a scintillat-ing fiber deteetor consisting of 3 x 128 fibers and a sein-tillator arrangement around the magnet for triggering pur-poses . The fibers are placed in a preformed thin Supportstructure with two overlapping layers twisting over thelength of the detector by 150° whereas the third layer isstraight . In Figure 1 two people from the Jülich workshop
are shown mounting the fiber seintinators, whereas Fig-ure 2 gives a picture of the lower part of the fiber detectorwith e'te pheInmultipliers and prearrq `ifiers
inted.
Figure 2 : The Jülich seintinafing fiber detector aftermounting the photomultipliers and preamplifiers.
During the firnt test runs at the AD/CERN the detec-tor components fulfilled the design values . All channelswere working with a background rate in accordance withthe flux from cosmic radiation . A burst of injected an-tiprotons showed a significant coincidence between thefibers and the outer scintillator system.
References:
[1] Proposal of the ATRAP collaboration, CERN-SPSC97-8/P306
[2] Ellis, N.E. Mavaromatos and D .V. Nanopoulos,Phys . Lett . B 293 (1992), 142V. Kostelecky and R . Potting, Phys . Rev. D 51 (1995)3923
[3] J . Bojowald et al ., Annual Report 1998, Jül-3640,p 54D. Grzonka et al ., Annual Report 1998, Jül-3640,p 55
71.
Charge state of exotic atoms formed from the malennies N2 arid 02
D.F . Anagnostopoulos,
Augsburger', G . Borchert, D . Chatellard a , J .-P. Egger a ,D .Gotta, P.Hauserb , P . Indelicato', P. ElsKhoury', K .Kirch b , T. Siems, L .M .Simons b
In pionic and muonic nitrogen and oxygen a signif-icant broadening of the (5g-4f) X-ray transitions of4 .0 keV has been observed by using a high-resolutioncrystal spectrometer [1, 2] . The contribution to theline width exceeding the experimental resolution asdetermined from the width of the trNe(6h - 5g)transition (4 .5 keV) is interpreted as the Dopplerbroadening stemming from the Coulomb repulsionof the ions at the time of separation of the diatomicmolecules . The widths of the muonic oxygen and thepionic nitrogen transitions were found to be equalwithin the error bars.The line shapes of the rrNe, rrN and p0 transitionshave been analyzed in detail using 3 different Braggcrystals (labeled Z15, Z30, and Z31) in order to ex-tragt the contribution dEo from the total line widthof the rrN and p0 systems (Figure 1) at the time ofthe emission of the X-ray [3] . From that quantity, thevelocity and potential energy q 1 q 2 /r is caIculated.The results show evidence for a pressure dependencewhich, however, needs further experimental clarifica-tion (Table 1).
Tobte 1 : Coulomb explosion parameters .
the Bragg crystal . Hence, the additional width of thetransitions in nitrogen and oxygen originates fromprocesses owing to the molecular nature of the tar-get.
Figure 1 : Position spectra of pionic Ne(6h - 5g) andN(5g - 4f) transitions measured with two differentapertures for the Si (220) Bragg crystals.
crystal p ZlEc v/c qle/r q l q 2/e/mbar /meV /10-6 /eV
rrN (5g -4f) Z15 095 620 773 24 1 74 95± 3 _I 119± 8
22 9 .2±0 .6_ 1 .71000 765 47 1 748 94 ± 6
1
-P- 4 117 ± 14
1241 9 .0 ± 1 .1 +0als+ 182500 951 ± 23 - 62 117± 3 ±7 182± 81 24 +0 .813.9±0 .7
.5
Z30 095 1000 805 30 6+1 1 7-1 99± 3 +142-2 .8130± 11
365 10.0±0 .8+001160 1000 855 ± 26 2-15222 105 ± 3 +146-1.7146 ± 8
4161 11 .2 ± 0 .6+1'2Z31 095 1050 789 ± 30 1- 2 . 97± 3 115 125± 8 1- 38 9 .6±0 .7 ' 2 .69
p0( 5g - 4f) Z15 095 1050 992 ± 98 _-T7'7 123 ± 12 +29-34 230 ± 45 +95 19 ± 4 1 9
The charge produa q 1 q2 of the recoiling systemswas calculated from the potential energy assum-ing the fragmentation distance r 12 to be equal tothe molecular bond length (ro t = 2 .283 a .a . andr N2 = 2.074 a .a .) . The symmetric error is statisti-cal only . The systematical error is due to the var-ious assumptions an the fitting procedure and theparametrization of the response function as derivedfrom trNe. The high charge state derived from theDoppler width indicates a very fast depletion of theelectron shell by Auger emission.The width of the pionic nitrogen line does not changewhen the reflecting area of the Bragg crystals isreduced from 095 mm in diameter to 60 mm hori-zontally by a diaphragm, whereas the pionic neonmeasurements show distinct differences when the di-aphragm is applied (Fig .1) . The larger line widthwhen using the large crystal area is attributed to theabberation due to the finite horizontal extension of
References:
[1] T. Siems, thesis, University of Cologne, 1997.
[2] Annual report, IKP 1997, p . 85.
[3] T. Siems et al ., submitted to Phys . Rev . Lett.
Institut de Physique de PUniversite de Neuchätel,Switzerlandb PSI,Villigen, Switzerland
Lab . Kastler-Brossel, Universit y P. et M.Curie,Paris, France
72
On-Iine control of the Jülich high-precision Bragg
eter
N. Dolfus, D . Gotta, H . Labus, H. Rangen (ZEL)
At the Paul-Scherrer-Institut (PSI), VHligen, high-precision measurements are being performed of thec eristic X-radiation emitted from Iight pionic andmuonic atoms aiming at the determination of thecharged pion mass to about lppm [1] and of the pion-nueleon s-wave scattering lengths to better than 1% [2].Both experiments use the high-precision version of theJülich reflections crystal spectrometer in combina-tion wich the cyclotron trap of PSI and a large CCDarray for positionssensitive X-ray recording in the fewkeV range
The above-mentioned precision experiments rely onan ultirnate control and stability of the irnaging geome-try of the spectrometer . The repeated change betweencalibration and measuring positions requires in addi-tion a high reproducibility and a convenient handlingto meet die complex demands for the Operation at amüde accelerator site.
The spectrometer control enelosesposition control as measured with high-precision
angular encoders and linear potentiometers,rotations and linear movements provoqued by
stepping and DC motors attaehed to precision lineartables, and
temperature measurements of Bragg crystals, vac-uum chamber and die CCD array and dyostat
As a matter of principle, all the movements and themeasurement of positions and angles are completelyindependent . The actual positions and angles are dis-played continuously and are changed on operator'srequest only . All actions can be performed remotely.The spectrometer can be used in a one or two crystalset-up.
The accumcy in die energy determination reachablewith the apparatus shown in Fig. 1 is basically given by
Fig. 1 : Sketch of die crystal spectrometer set-up at PSIthe stability of the angle between the crystal planes and
and the MOVE and CO
OL options as de-the X-ray detector, which is directly related to die
scribed in the Table below.Bragg angle . This angle, measured by a angular en-
coder having a resolution of 0 .13 " [3], is compwith a preset value and is kept within the resolution binof the en er by a piezo ceramics.
The spectrometer control is realized with thephical programming environment LABVIEW 5 .1
rumfing on a standard Win95-PC. The data aquisitionand control hardware for the stepper motors and dieangular encoders consists of ISA-boards from - erentsuppliers . The LABVIEW drivers for the encoders weredeveloped at our ZEL-departrnent. All other about 25actors and sensors, i .e . crystal adjusünent, temperatureand presse measurements, are eontrolled by the FieldPoint Modular U0-System from National Instrumentsvia a RS-485 Schal Bus.
Fes,
A Bragg angleB source positionC relative angle crystals 1 & 2D vertical angle of crystalE fluorescence targetF CCD f length
emss-hair masktransverse offset
G temperatures - crystal(s)
remote MOVESstepping motor & linear table & PIEZO stackstepping motor & linear tableDC motor (2 crystal set-up only)DC motorstepping motorDC motorDC motor
CONTROLangular en er ± 0.13"angular eneoder ± 5"linear pah ± 0 .005°linear pot 0 .005°linear pot ± 0 .5 mmlinear pot ± 0 .1
°linüt svviteheslinear gauge ± 0 .5 !am
front & rearvacuum ehamberChip supportcooling shieldLN2 dewar
H temperatures - CCD array
[1] D.F.Anagnostopoulos et al ., PSI exp . R-97 .02[2] G.C.Oades et al, PSI exp . R-98 .01
[3] RON 806, Haidenhain, D-83292 Traunreut
73
High-rate X-ray detector for exotic atom spectroscopy
A . Ackens a , U. Clemens', H . Gorke', D . Gotta, H . Loevenich a , D. Maeckelburg a , M . Ramm', K . Zwoll a
The high pion and muon fluxes at modern meson fac-tories allow the precision spectroscopy of the char-acteristic X-radiation from exotic atoms with highstatistics . In the last years, Charge-Coupled Device(CCD) detectors are used more and more for X-raydetection.Based an the technology of fully depleted CCDs (pn-CCD), a compact and flexible low-noise control- andread-out-system has been developed . The pn-CCDis a new type originally developed for applicationsin space for X-ray astronomy [1] . lt is designed toperform extremely fast, high-resolution spectroscopyof photons in the soft X-ray region at ultimate effi-ciency . The system allows an image repetition rateof up to 220 frames/s for a CCD of 64 x 200 pixels(3 cm 2) and is limited only by the read-out speed ofthe 64-channel amplifier chip (CAMEX [2]).The pn-CCD camera system reaches event rates ofup to 10' events/s em 2 with a repetition rate ofup to 660/s hy using a small pn-CCD with 64 x60 pixels (Talsiel) . First experience has been gainedfrom measurements of antiprotonic X-rays from lightelements with a reduced frequency of 30 frames/s [3] .
For the analog and digital support of the camerasystem and its 12-bit flash-ADC, 10 different eu-rocards have been designed, which are located ina single crate (Figure 1) . All parameters like pulse-sequencing, power-up and -down of the 24 variableand 16 fixed Power supplies are completely controlledby a front-end system with hard-wired interpreters.The program codes for these interpreters are devel-oped and down-loaded from a supervising work sta-tion. CCD set-up and optimization are done inter-actively by the operator . The front-end system andthe computer are coupled via a fiber optic link witha PCI-bus interface . Besides the generation of theabove-mentioned timing sequences, the meint driveninteractive program system (running under Linux)serves to set up the user's experiment, visualize andstore the data.
References:
C. von Zanthier et al ., Experimental Astronomy,vol .8 (1998) 89
[2] W. Buttler, G . Lutz, H. Bergmann, H . Dietl,D. Hauff, P. Hon, P . F . Manfredi, Nucl .Instr.Meth . A 273(1988) 778
Table 1 : Characteristics of the small pn-CCD chip .
[3] H. Gorke, thesis, University of Cologne, 1996
ZEL, FZ Jülich
Figure 1 : Set-up of the high-rate detector system.
pixel matrixpixel sizedepletion depth
64 x 60150 x 150 prri280 tim
quantum efficiency
> 90% at 0 .5 - 10 keVelectronic noise
<5e- at 3MHz
max. readout frequencymax. frame ratecharge handling capacityenergy resolution at 5 .9 keV
3 MHz660 frames/s10 -< 160 eV (FWHM)
74
Further Studies of the Roper Resonance
H . P. Morsch and P. Zupranski'for the SPES47r collaboration
The interpretation of the P 11 (1440 MeV) resonance ex-citation in aep scattering as a radial excitation of thermcleon l implies that this resonance is not excited byphotons . This, however, is in conflict with photon data(e .g . 7-p-+ zrN) where M1 strength has been deduced inthe Roper resonance region 2 . A way out of this problemwould be the assumption, that the Roper resonance con-sists of two resonances, a radial excitation seen in a-pand a Ml excitation excited in
This brings us back to the problem of the Roper reso-nance excitation 3 in a-p and 7r-N . In an attempt to de-scribe this resonance consistently in both systems, strongdiscrepancies in the resonance Parameters were observed,which could be resolved only by assuming two structuresin this resonance.
In order to see if this assumption resolves also the aboveproblem with photons, resonance cross sections were cal-culated for photo-induced reactions using T-matrix am-plitudes obtained from a consistent fit of all a-p and 7r-N data' . The clearest information an baryon resonanceexcitation in 7-N may be seen in the 27r° production,because here the non-resonant 7rtli production (which isvery strong in 7-p) is strongly reduced . Therefore, wemake a comparison with this reaction, for which gooddata exist from Mainz' . This is given in fig .1.
We see, that the firnt resonance, which is strongly excitedin a-p, is not seen in this reaction (this is given by thedashed line, which is normalized arbitrarily) However,the second resonance is excited with a strength consis-tent with 7r-N . This supports strongly our picture of adouble structure of the Roper resonance : the ferst N*structure (Saturne resonance) is indeed consistent withthe assumption of a radial excitation, whereas the secondstructure can be understood as a second order excitationof the A(1232 MeV) resonance.
These results can be tested further in exclusive a-p scat-tering which should exhibit a N* decay branching ratioTüte different from 7r-N . As in a-p only the radial modeis excited, we expect a dominant 27r(s)-N decay of thisresonance.
First results from SPES47r
Exclusive a-p scattering has been measured at Saturnewith the SPES47r detector" . Very preliminary resultsfrom this experiment show a strong 27r decay of the ob-served resonance, as is expected.
Soltau Institut for Nuclear Studies, P1-00681 Warsaw,Poland
Figure 1 : Calculated cross sections for the two Pr, res-onance structures from refs .3,4 in comparison with thedata from ref.5 . In the upper solid line a very smallnon-resonant rrA component as well excitation of theD13(1520 MeV) resonance (dot-dashed line) is included.
References:
1. H .P. Morsch et al ., Phys. Rev. Lett . 69, 1336(1992) ; H.P. Morsch, W . Spang and P . Decowski, Z.Phys . A 348, 45 (1994) ; and H.P . Morsch, Z . Phys.A 350, 61 (1994)
2. R. A. Arndt et al . Phys. Rev . C 42, 1853 (1990);53, 430 (1996)
3. H. P. Morsch and P . Zupranski, IKP/COSY Ann.Rep. 1998, p .57; and Proc . Baryons '98 (1999)p.130
4. H.P. Morsch and P . Zupranski, Phys. Rev. C (inprint)
5. Härter et al . Phys. Lett . B 401 (1997) 229
6. T .Hennino, R. Kunne et al . Nouvelles de Saturne17 (1993) 35 ; and IKP Ann . Rep .1995, p .127
..o
b
75
76
2 Nuclear Spectroscopy
78
Investigation of Magnetic Rotational Bands in 142 Gd with EUROBALL
R.M. Lieder, T. Rzaca-Urban1 , H. Brands, W. Gast, H.M. Jäger, L . Mihailescu, Z. Pytel', W. Urban', T. Morek',Chr . Droste', S . Chme12 , D . Bazzacco3 , G . Falconi 3 , R. Menegazzo 3 , S . Lunardi 3 , C. Rossi Alvarez 2 ,
G. de Angelis 4 , E . Famea 4 , A . Gadea4 , D .R. Napoli4 , Z . Podolyak4 ,
A study of high-spin states in the nucleus 142 Gd has beencarried out with the 7 -detector array EUROBALL 111 andthe charged-partiele detector array ISIS at the Labora-tori Nazionali di Legnaro, Italy. To populate high-spinstates in l"Gd the 99Ru(48 Ti,2p3n) reaction at a beamenergy of 240 MeV has been used . The level scheme of'"Gd deduced from this data set has been considerablyextended in excitation energy, spin and the number of ob-served cascades with respect to the scheme previouslypublished [1] . Spin-parity assignments result from an-gular distributions, DCO ratios, conversion coefficients,-y-ray polarization and decay patterns.Four dipole bands (denoted by DB and a number) havebeen observed for 142Gd in the present work . From theprevious work [1] the existence of three of the dipolebands was known but except for DB3 they were not wellestablished . From the present high-statistics results theknowledge an the dipole bands has been significantlyimproved . For an interpretation of the dipole bands asMR bands a comparison of their features with predic-tions in the framework of the TAC mode! [2] has beencarried out. Such features are the total aligned angularmomentum and the ratio of reduced transition proba-bilities B(M1)/B(E2) . The B(M1)/B(E2) ratios re-sult from a careful determination of the branching ra-tios of crossover and cascade transitions for the fourdipole bands . The dipole bands in 1420d can be asso-ciated with an oblate deformation of the nucleus . TRScalculations show minima for the deformation parame-ters ß 2 sei 0 .15 and -y -60° for a frequency rangeof 0.2 < hw < 0.5 MeV. For this deformation thehu /2 neutron-hole states with small values and theg7/2 proton-hole and h 1 1/2 proton states with large 9 val-ues contribute to the configurations of the dipole bands.A uh-
2/211rh1/2 configuration has been assigned to DB111
and a vh72 irh1/2g7/12 configuration has been assigned11/2
1to DB3 . The bands DB2 and DB4 result from the breakupof a second h11/2 neutron-hole pair . For these configu-rations TAC calculations have been carried out and theresults are included in fig . 1. In general, a reasonableagreement between the experimental data and the predic-tions of the TAC model has been obtained supporting theinterpretation of the dipole bands in ' 2 Gd as magneticrotations . The B(M1)/B(E2) ratios of DB1 and DB3are, however, underestimated.The work was in part funded by the EU (contractno. ERBFMRXCT970123), the Volkswagen Founda-tion (contract no. 1/71 976), the KBN (Grant no.2P03B 05312) and by the Foundation for Polish Science.1 Institute of Experimental Physics, University of War-saw, PL-00-68 1 Warszawa, Poland2 Institut für Strahlen- und Kernphysik, University ofBonn, D-53115 Bonn' Dipartimento di Fisica and INFN, Sezione di Padova,1-35131 Padova, Italy
142Gd
DB3
160 .2
03
0 .4
03
0.6
0.7
-hü) (MeV)
100 -
DB4
o16
18
24
22Spin
Figure 1 : Upper portion : Total aligned angular momen-tum vs . rotational frequency and lower protion:B(M1)/B(E2) ratios vs. spin for the dipolebands in 142 Gd. The lines result from TACmodel calculations.
4 INFN, Laboratori Nazionali di Legnaro, 1-35020 Leg-naro, Italy
References:[1] M. Sugawara et al ., Z . Phys . A358 (1997) 1[2] S . Frauendorf, Z . Phys . A358 (1997) 163
25 1-
80
60
15 -
to -
-A> DB1
DB3
142Gd
DB2
79
Study of quadrupole moments of superdeformed bands in 1"Gd
T. RzacatUrban', A . Pasternak 1,2 , R .M. Lieder, W. Urban', M. Rejmund', Z. Mareinkowskal , R. Marcinkowski',S . Utzelman, H .J . Jensen, W. Gast, H. Jäger, D . Bazzacco3 , S . Lunardi 3 , N.H. Medina 3 , R . Menegazzo 3 , P. Pavan 3 ,
C .M. Petrache 3 , C. Rossi Alvarez3 , G. de Angelis4 , D .R. Napoli 4 , L . Zhu 4 , A. Dewald5 , S . Kasemann'
Three superdeformed (SD) bands have previously beenfound in 1"Gd [1] . The yrast SD band in 1" Gd shows asmoothly decreasing dynamic moment of inertia with in-creasing rotational frequency. The first excited SD bandshows two subsequent band crossings at rotational fre-quencies of ae0.4 and 0 .68 MeV. In the framework ofthe cranked Woods-Saxon-Strutinsky approach a tr62 v7 1configuration has been assigned to the yrast SD band witha deformation of ß2 = 0.523 and a tr62 v[642]5/2 v7oconfiguration to the first excited SD band (ß 2 =0.508) in145 Gd between the band crossings [1] . The second ex-cited SD band has been identified as the signature partnerof the first excited SD band . To check this interpreta-tion quadrupole moments have been measured for the SDbands in' 45 Gd.
1.00
0.95
aoo0.85
0.75
0.70
0 .65
Figure Experimental fractional-shifts F(r) as functionof -y-ray energy and theoretical F(r) curves forvarious values of the quadrupole moment Qofor the yrast SD band (upper portion) and thefirst excited SD band (lower portion) in ' 45 Gd.
Mean lifetimes have been measured for superdeformedbands of ' 45 Gd with the Doppler-shift attenuationmethod . High-spin states in '45 Gd have been popu-lated in the 114 Cd(3fi S,5n) reaction at a beam energyof 182 MeV. The beam was provided by the LaboratoriNazionali di Legnaro . The initial recoil velocity was
vo /e 2.5%. The target consisted of a 1 .2 mg/cm 2"4Cd fall evaporated an a multi-layer backing . The re-coiling 145 Gd nuclei were slowed down and stopped inTa and Bi layers with thicknesses of 1 .2 mglern 2 and55 mg/cm 2 , respectively. The backing was Chosen in sucha way that the deexcitation of the SD bands occurred dur-ing the showing-down process . The ty-rays were detectedusing the GASP array. Its 40 Ge detectors are placedsymmetrically with respect to the beam direction in sevenrings at angles of 35°, 60°, 72°, 90°, 108°, 120° and145° . Spectra showing the Doppler shifted SD lins havebeen produced for these angles . In order to extract thelifetime information from these spectra the fraction of thefull Doppler shift F(r) v/vo has been determined foreach transition . The mean quadrupole moments of theSD bands have been deduced by comparing the experi-mental F(r) values with predictions for various values ofthe quadrupole moment . In fig . 1 experimental and the-oretical F(r) values are plotted vs . y-ray energy for theyrast and first excited SD bands . Quadrupole moments ofQ 0 = 11.8 ± 0 .8 eb (ß2 0 .48) and Q0 = 13.5 ± 1 .0 eb(ß2 = 0.53), respectively, have been found for thesebands . The second excited SD band was populated toweakly to deterrnine the quadrupole moment.The deformation deduced from the quadrupole momentof the yrast SD band in is smaller than thatof the first excited SD band contrary to the expecta-tion from the previous configuration assignment . In or-der to assign configurations to the SD bands which arein agreement with the observed quadrupole momentsa comparison with theoretical quadrupole moments hasbeen carried out . lt was demonstrated in the erank-ing Skyrme-Hartree-Fock model [2] that, independentlyof intrinsic configurations and proton and neutron num-bers, the quadrupole moment of a SD nucleus in the
150 region can be calculated very precisely withrespect to the doubly-magic SD core nucleus ' 52 Dy interms of the contributions of the individual hole and par-fiele orbitals . The new configuration assignments aretr6 1 Ir[404]9/2 v[514]9/2 v7° for the yrast SD band andtr6 2 v[642]5/2 v7° for the first excited SD band betweenthe two crossings in 14 ' Gd.This work was supported by the Polish State Committeefor Scientific Research (KBN) under grant 2P03B 05312and by the Volkswagen Foundation under the contractnumber 1171976.1 LEP, University of Warsaw, Warszawa, Poland2 loffe Institute, St . Petersbourg, Russia3 INFN, Sezione di Padova, Padova, Italy' INFN, LNL Legnaro, Italy5 IKP, Universität zu Köln, Köln, Germany
References:
[1] T. Rzaca-Urban et al ., Phys . Lett . B 356 (1995) 456[2] W. Satula et al ., Phys . Rev . Lett . 77 (1996) 5182
1 .00
0.95
0.90
0 .55
o .so0 .75
0.70
0.60700
iihAT'u''
14 .0
12.5
11.0
1000 1100 1200 1300 1400 1500
E y(keV)900
80
From Iüghly to superdeformed shapes : study of 1424"Gd
R.M. Lieder, T. Rzaca-Urban', H. Brands, W. Gast, H.M. Jäger, H.J . Jensen, L . Mihailescu, Z. Pytel', W. Urban',Ch. Droste', T. Morek', D . Bazzacco2 , S . Lunardi2 , R . Menegazzo2 , C. M. Petrache 2 , C . Rossi Alvarez2 ,
G. de Angelis3 , D . R . Napoli3 , E . Farnea 4 , A. Gadea4 , Z. Podolyak4 , Ts . Venkova4 , R . Wyss 5
lt is well known that highly-deformed bands (ß2
0.35 - 0.40) exist in nuclei with A ae 130 and su-perdeformed bands (ß2 Ra 0 .50 - 0 .60) in nuclei with
150. In order to study the transition betweenthese two regions the nuclei l"''"Gd have been in-vestigated since highly-deformed bands are known in139 .144' Gd and superdeformed bands in " 44'53 Gd. High-spin states in 142,143 Gd have been investigated with the -y-spectrometers EUROBALL and GASP, respectively andthe chargedspartiele detector array ISIS at the Labora-tori Nazionali di Legnaro, Italy . The 99 Ru( 43 Ti,2p3n)and "Mo(" V,p4n) reactions at beam energies of 240 and238 MeV, respectively, have been used.
142Gd
44(34»
11571 (69/2»982 (65/2 +)1007
(61/2+)
(57/2+)1025 153/2'812 49/2+629 45/2t-1-r 41/2+818 37/2+733 33/2 +628 29/2,559 25/2*-3-5i9 21/2'
36 17/2'743 13/2+
j 11/2-12 s
Figure Collective bands in '42443 Gd.
In 1" Gd a superdeformed band has been Mund . lt has anintensity of < 0 .3% and is hence ,,:ei 4 times weaker thanthe superdeformed yrast bands in '44,145Gd. Candidatesfor highlysdeforrned bands in 1" ,'Gd are shown in fig.1 The stretched E2 cascades have been extended consid-erably with respect to previous publications [1, 2] Thespin-parity assigrtments are based an the analysis of DC0ratlos and linear polarizations . A plot of the total alignedangular momentum I,, as function of the rotational fre-quency hw for the bands in 142443 Gd is shown in fig . 2.For comparison the highly-deformed band in '"Gd [3]and the triaxial band in ' 44 Gd [4] are shown as well . Thesequences in " 2443 Gd behave similarly to that in 'Gdbut quite differently tarn the band in ' 39 Gd .
Figure 2 : Total aligned angular momentum vs . rotationalfrequency for bands in 139,142-'Gd.
The transition from highly-deformed to superdeformedshapes is expected to occur via triaxial shapes . The weakintensity of the superdeformed band in 1" Gd seems to in-dicate that the superdeformed structures move to higherexcitations energies below N = 80 . The vanishing ofhighly-deformed bands beyond N 77 probably oc-curs through the development of triaxial shapes . Thestretched E2 sequences in '" , '"Gd have oblate defor-mations at the band heads and show two band crossingseach at hw Pur' 0 .38 and 0 .50 MeV, respectively. They arecaused, according to total-Routhian surface calculations,by the alignrnents of h9/2 and i13/2 neutrons, which drivethe nuclear shape to a wellsdeformed, triaxial minimum
= 0 .25, = 26 .5°).The work was in part funded by the BMBF under the con-tract number 06JU670, by the Volkswagen Foundationunder the contract number 1/71 976, by the KBN GrantNo. 2PO3B 05312 and by the DFG under the contractnumber 436 BUL 113/75/0.' MP, University of Warsaw, Warszawa, Poland2 INFN, Sezione di Padova, Padova, Italy3 INFN, LNL Legnaro, Italy4 INRNE, BAS, BG-1784 Sofia, Bulgaria5 RIT, Physics Department Frescati, Stockholm, Sweden
Referenees:
[1] M. Sugawara et al ., Z . Phys . A358 (1997) 1[2] M. Sugawara et al ., Pur . Phys . J . Al (1998) 123[3] R. Ma et al ., J . Phys . G 16 (1990) 1233[4] T. Rzäca-Urban et al ., MIM . Phys . A579 (1994) 319
0.7
1309
11231 (28 +)956 (26»9401(24»
9801 22+
911+ 20 +790 18+
14+741 t 12+
3165 54 10+0.37 ns
1842 16 +
15
143 Gd
(73/2+)
1189
35
25
20
15
lo
81 .
Rattern Recognition Method for -y-Ray Traeking Detectors
L. Mihailescu, W. Gast, R .M. Lieder, M . Rossewij
A spatial localization and energy determination of multi-ple Compton scatterings and photoelectric events in largevolume Ge detectors is required for tracking and for anestimation of the initial direction of the impinging [-y-ray. Digital methods for on-Iine analysis of the currentpulses from segmented coaxial HPGe detectors were in-vestigated . By a shape analysis of the segment pulses, lo-calization of the interactions can be obtained with a goodradial resolution, as well as with an azimuthal resolutionsuperior to that due to detector segmentation.For an estimation of the pulse shapes produced by in-teractions at different points, the Charge collection pro-cess has to be accurately known . Experimental and simu-lated pulse shapes suggest a strong influence of the elec-tric conductivity anisotropy associated to the crystal ori-entation on the Charge collection process [1] . Besidesthe anisotropy, the complicated spatial distribution of theweighting fields of the segments contributes to the induc-tion of rather complex pulse shapes in the detector elec-trodes, depending on the azimuthal and radial Position ofthe iy-interaction . For on-Iine analysis of the detector sig-nals, new digital methods for signal triggering, as wellas for event timing with sub-sampling interval resolutionwere developed . To localize spatially the interactions, thedigital signal is further processed and transformed into anorthogonal space using Haar wavelets.The complexity of the pulse shapes requires the use ofa pattem recognition method for the identification of theinteraction positions . In this way, features of the exper-imental shapes are compared with the pattem featuresstored in a data base, and the most probable pattem isChosen . After doing this step for each of the detector seg-ments, the results are combined by calculating a correla-tion value from the information obtained for each detec-tor, and finally, the interaction positions of the multiplescatterings are determined.The employment of highly discriminatory features is thekey to a successful recognition system . With the Haartransform of the pulse shapes, one can satisfyingly ex-tract the features characterizing the signal . Another ad-vantage of using Haar transforms consists in an efficientanalysis of the pulse shape at a time scale appropriate tothe experimental SIN ratio.An example of a pattern recognition analysis is presentedin fig . 1 . Examples of pulse shapes taken into account areplotted in fig . 2, and their Haar wavelet coefficients in fig.3 . In this example all four interactions were accuratelyidentified . However, the pattern recognition system runspoorly for more than two interactions in one segment, andit can not distinguish between dose interactions within asegment.Work supported by the EU under the TMR Network con-trau ERBFMRXCT970123
References:
[1] L. Mihailescu et al ., Nhd. Instr . Meth . A, acceptedfor publication (1999) ;
Figure 1 : Four simulated interactions within a detectortogether with the identified positions . (Crosssection of a cylindrical Ge detector .)
Figure The pulse shapes of the segments 4, 5 and 6.
Figure 3 : Haar wavelet coefficients of the segments 4, 5and 6 corresponding to the pulse shapes shownin fig . 2.
[
[-- er
[
[
[
[
[
t
r
13ö--'2251 4j 38i 400
time
82
Development of a fast PPADC module
M. Rossewij, W. Gast, A . Georgiev', H . Brands', J . Stein'
The Pulse Processing Analog to Digital Converter(PPADC) has been developed to acquire the data from thehext generation of high resolution multi-detector arraysfor nuclear spectroscopy employing highly segmented -y-ray tracking detectors . To allow real time pulse shapeanalysis, a fast version of the PPADC is under develop-ment.The present system consists of a PCI/ISA motherboardonto which up to eight PPADC processing channels canbe plugged as daughterboards (subboards) . The mother-board [1] is responsible for the read-out and control of thedaughterboards, making histograms and communicatingwith the host (PC) via PCI or ISA. A motherboard, pro-vided by target systemelectronic GmbH, was assembledand tested.Two daughterboard versions have been developed by tar-get systemelectronic GmbH. Both versions contain allhardware needed for large dynamic range, high resolu-tion signal processing . The 20 Msps version [1] has a 12bit 20 Msps ADC and 2 DSPs. To allow pulse shape anal-ysis, higher sampling rates are required . Therefore, a pro-totype of a faster version has been developed which hastwo 40 Msps ADCs, one PLD and one DSP (see fig .!).This prototype has been assembled and is currently beingtested.
Figure 1 : Blockdiagram of the fast PPADC daughterboard.
The PPADC software can be divided in three parts:1. PC software . (sarge tIFZ Jülich development)2. DSP software . (target development)3. PLD software. (EZ Jülich development)The PC software and the PLD software will be discussedin more detail now.PC softwareWhen the PPADC is operated with the PCI bus, it ismapped on the PC CPU memory. Under windows, adevice driver is required to determine and access thePPADC physical addresses . Since the MTM-driver [1]was not available anymore, a driver (DMCAPCI.was written which could be called from 16 and 32 bitW9x applications . This driver maps virtual memory tothe physical PPADC addresses and provides for the 32bit application a virtual address (see fig .2) and for the 16bit application a selector (in C, the selector can be con-verted into a far pointer) . For NT, a commercial availabledriver [2] is employed which provides the NT application
with a virtual address or functions to access the PPADC.To be able to use the same saurees on different OS plat-forms, the OS dependent parts are encapsulated.
PPADCMotherboard
,-,:l
c M̀0
Figure 2 : Driver.
For the different OS platforms, three applications aremade:1 dmcastatus .exe: Informs about the number of moth-erboards and daughterboards in the system and whetherthey are running correctly.2 testdmca .exe : Allows the user to read from and Write tothe memory of the motherboard and daughterboard DSPs.Also the motherboard FLASH and daughterboard EEP-ROM can be accessed.3 wintmca .exe : This windows program can be used tocontrol and monitor a data acquisition system. lt canshow the acquired spectra and store them to disk . Thewintmea program, developed by target, was already ex-isting but has been extended to handle the data comingfrom the PPADC system.ALTERA PLD softwareTwo PLD modules have been designed:1) A module to communicate with the daughterboardDSP2. This module is compatible with the 56303 host-poft (HI8) allowing to keep the communication softwarerunning on DSP2 unchanged . This module has been sim-ulated and tested.2) A trigger module optimized for low threshold signals.This module has been simulated only.
This work is supported by the EU in the framework of theTMR Network contract ERBFMEXCT-970I23, and by1 1B of the Forschungszentrum Jülich in the frameworkof the technology transfer project 'ITB/V.292.03 .92.
' target systemelectronic GmbH, Solingen, Germany
References:
[1] IKP Annual Report (3640) 1998 p .203[2] DSP56301-Treiber für Windows NT, V3 .7, 09 .01 .00
NT, 32 bitapplication
virtauladdress
W9x, 16 bitapplication
elector
W9x, 32 bitapplication
virtauladdress
301 .sys
DMCAPCI .VXD
PPADCMotherboard
6->0
r0
äto
83
Invesfigation of DC0 ratios and linear polarization of y rays in "'Gid with EUROBALL
T. Morek', Ch . Droste' R.M. Lieder, T. R2,Na-Urban', H. Brands, W. Gast, D.M. Jäger, L . Mihailescu,Z. Pytel', W. Urban', D. Bazzacco 2 , G. Faleoni', R. Menegazzo2 , S . Lunardi2 , C. Rossi Alvarez',
G. de Angelis', E . Farneal, A . Gadea3 , D .R. Napoli 3 , Z . Podolyak'
Directional correlation (DCO) ratios and linear polar-ization of 7-transitions in '2 Gd have been investigatedwith EUROBALL (cf. contributions to this annual re-port) to establish their multipolarites and mixing ratios.In this analysis the 26 CLOVER detectors positioned intwo rings at average angles of 0=76.72' and 103 .28°, fiveCLUSTER deteetors at 0=15 .45' and five tapered detee-tors at 156 .76° were used . All possible combinationsof the angle so between these detectors were taken intoaccount . An asyminetrie angular-correlation matrix wassorted for this geometry. Because a stack of thin targetswas used in the experiment the excited nuclei were recoil-ing into vacuum. For the Jong lived states a disappearanceof the alignment by deorientation was observed . There-fore, the angular distribution of 7-transitions below the1 = 10+ isomers (0 .37 ns and 3 .4 ns) and the 7- iso-mer (0.14 ns) in ""Gd became fully isotropie . As result,two kind of angular correlations have been observed: (i)directional correlations when both y-rays were emittedfrom oriented states and (ii) angular distributions (AD)when one 7-ray was emitted from an oriented state andthe other one from a fully deoriented state . Appropriate
RDCO ratios or RAD values were calculated as:
R
N(01,71 ; 02, 72 ; 99)/N(02,71 ; 0 1,°y2 ;4
where 0 1 sa15' and 92 iaa 90° ; = gated transition and y2
= observed transition. The RAD values da not dependan the character of the delayed transition . To check theassumption of a strong deorientation effect, the R valuesfor the known E2 transitions were determined by gatingan E2 transitions below the isomers . When the observed-y-transition was also below the isomer then R = 1, butwhen it was above the isomer then R ,,e I .3 . For the ge-ometry under consideration a value of RAD ''e 1 .32 isexpected for stretched E2 transitions when the width ofthe substate population distribution is cr/I = 0.4 andRAD sie. 1 .42 for o-/I = 0 .3.The linear polarization of -ystransitions in ' 42Gd wasdeduced using the CLOVER deteetors working as po-larimeters . Two y - 7 matrices : VERTICAL (V) andHORIZONTAL (H) were sorted . The V (H) ma-trix contains the events in which one 7-quarit is Comp-ton scattered in the direction perpendicular (parallel) tothe emission plane [1], registered in two segments of aCLOVER detector, whereas the second 7-ray was regis-tered in any Ge detector of EUROBALL . From the V andH matrices the number of perpendicular NJ_ and parallelNil scattered events were deduced, respectively . Thesequantities allow to determine the linear polarization P of7-rays using the following relation [2]:
P = 1/Q x
Nil )/(aNi
(2)
where Q is the polarization sensitivity of the CLOVERdetector [2] . To check the relative efficiency and tl'eenergy resolution of the CLOVER deteetors and to de-termine the correction factor a we used dato from a
's2Eu source . The measurement allowed to select the13 CLOVER detectors with die best resolution . For thisgroup of deteetors the average value of a was found to bevery dose to 1 with ±l% accuracy for 7-rays from 0 .24to 1 .0 MeV.
Figure 1 : Polarization P vs. angular distribution ratioRAD for the (+, 0), band and die dipole bandsDB1 arid DB3 in 142Gd. Theoretieal values arealso shown.
Results of the analysis for stretched E2 transitions of the(+, 0) 1 band and for members of the dipole bands DB 1and DB3 in 14 ' Gd are shown in fig . 1 in a plot of die po-larization P vs . the angular distribution ratio RAD . Forcomparison, fig . 1 contains also results of calculations forthe used geometry, viz . for pure stretched El and E2 tran-sitions and mixed M1/E2 transitions assuming 0 .3(dashed curve and symbols) and 0 .4 (solid curve and sym-bols) . The MI/E2 curves represent the dependence of Pand RAD an the E2/M1 mixing ratio B . From the datopoints for the stretched E2 transitions of 544, 741 and834 keV in die (+,0) 1 band o-/I = 0 .4 can be deduced.The dato points for the dipole bands DB1 (301, 360, 381,427 keV) and DB3 (286, 295, 374, 527 keV) are in agree-ment with the assignment of pure Ml or mixed E2 1character with b' -0 .1 . A pure stretched El characterof these transitions can be excluded.The work was in part funded by the EU (contractno. F'MRXCT970123), the Volkswagen Founda-don (contract na. 1/71 976), the KBN (Grant no.2PO3B 05312) and by the Foundation for Polish Science.
LEP, University of Warsaw, Warszawa, Pol and2 INFN, Sezione di Padova, Padova, Italy' INFN, Laboratori Nazionali di Legnaro, Legnaro, Italy
References:
[1] Ch. Droste et al ., Nucl . Instr. Meth . A378 (1996) 518[2] K. Starosta et al . Nucl . Instr. Meth . A423 (1999) 16
84
gs
S' Hd ADU3N3 IH ONV
-£
86
3. MEDU ND H EN R Y PH SICS
88
Pion form factors in the presence of virtual photons
B . Kabis and Ulf-G . Meißner
In chiral perturbation theory (CHPT), which is theeffective theory of the Standard Model [1], most ob-servables and processes in the two flavour sector havebeen worked out to two-loop accuracy, either by di-rect Feynman graph calculations or making use ofdispersive methods. In most cases these two-loopcorrections are sizeably smaller than the correspond-ing one-loop terms, as expected by the power count-ing underlying CHPT . However, as first pointed outin ref.[2] and further quantified in reh[3], electro-magnetic corrections to elastic rtr-scattering in thethreshold region are of the same size as the hadronictwo-loop contributions. At the level of the presentlyachieved accuracy, it is therefore mandatory to in-clude virtual photons and work out the dual effectsof isospin violation due to the light quark mass differ-ence and the electromagnetic interaction . The vectorand scalar form factor of the pion as well as pionicmatrix elements of the energy-momentum tensor inthe presence of virtual photons have been workedout in ref. [4] . The scalar form factor is of interestfor various reasons . Due to its quantum numbers,its phase is related to the strong Irr interaction inthe isospin zero S-wave and it also exhibits the uni-tary cusp at the opening of the two-pion threshold.Furthermore, it gives a direct measure of the QCDquark mass term in the pion . In addition, the malmform factor plays an essential role in the dispersiveanalysis of the so-called pion-nueleon c-term . lt istherefore mandatory to evaluate the effects of vir-tual photons on this scalar-isoscalar quantity. Sim-ilarly, the hadronic two-loop representation of thevector form factor is extremely precise and the elec-tromagnetic corrections have to be calculated . An-other set of form factors is related to the pion matrixelements of the energy-momentum tensor [5], whichplay a role in the decay of a light Higgs into two pi-ons or heavy quarkonia transitions into the groundstate with the emission of a pion pair . Of particularinterest is the trace of the energy-momentum tensorwhich allows one to study the interplay of conformaland chiral symmetry or the hadron mass composi-tion . Clearly, it is of interest to learn about the mod-ifications induced by virtual photons, although oneexpects these to be small effects . Of course, when-ever one deals with virtual photons, one encountersinfrared (IR) singularities due to the vanishing pho-ton mass . These divergences can be cured by tak-ing into account the effects of soff photon radiationwhich have an energy below a given detector resolu-tion . For that, one has to consider cross sections ordecay widths . For the vector form factor, one relevantprocess is e+ e - 7r + 7r- . The leas easily accessiblescalar form factor together with the form factor ofthe trace anomaly can be studied in the decay of theHiggs boson into two pions . Note that to fourth orderin the chiral expansion, one has to consider only the
radiation of exactly one soff photon from any one ofthe final-state pion legs.Consider first the results for the vector form fac-tor of the pion, including photon loops and elec-tromagnetic counterterms . The various electromag-netic corrections, which are grouped into reducibleas well as irreducible photon loop graphs, electro-magnetic counterterms and IR finite bremsstrahlungterms (see ref.[4] for a detailed discussion) are typ-ically a few percent of the strong fourth order con-tribution . The different contributions tend to cancel.One can also deduce the electromagnetic correctionsto the pion Charge radius (for comparison the fourthorder strong result is also given),
M,±
( 1 )
with a e 2 /4rr 1/137 .036 the fine struc-ture constant . Note that the irreducible photonloop contribution has vanishing slope at zero mo-mentum transfer . This is an accidental effect.The numerical results for these various contribu-tions are (r2)r,st,ng0 .442 fm2 , (r»,,v,phgton
-0.0002 fm2 , and (r 2 ) flnite 1R = 0.024 (0 .018) fm2 ,for ,1.XE 10 (20) MeV. We use 93 MeV,114* = 139 .57 MeV and 16 = 16.5. One way of deal-ing with the resolution dependent IR contribution isto follow the arguments which have been used in thediscussion of scattering [3] . While the cross sec-tion of course depends on the detector resolution andthus the scattering length a, du/d9 = la!» one candefine an electromagnetically corrected scatteringlength which is independent of AE. This is achievedby absorbing the resolution dependent terms into theappropriately redefined phase space . Such a proce-dure applied here would essentially amount to drop-ping the last term given in eq.(1) . We conclude thatthe intrinsic virtual photon effects on the pion vec-tor form factor in the low energy region are tinyand sizeably smaller than the two loop effects cal-culated in refs .[6, 7] . In refl . [6, 7], also the quadraticterm in the Taylor expansion of F'(s) according togr(s) = 1 + i,(r»,v s + cr s 2 + 0(s» was consid-ered . Counterterms to fit experimental values of c .,,.vexactly only appear at 0(q 6 ), and indeed the findingin [6, 7] is that the 0(q4) calculation is completelyinsufficient to describe er, with the final value dom-inated by an 0(q6 ) counterterm . Here, we might ei-ther check whether this large 0(q6 ) contribution canbe reduced when taking into account the electromag-netic corrections, or we can give credit to the two-loop analysis in case these again turn out to be very
( 2)VIr,strong
(47rF)2 \ l61
v7r,photon
v7r,finite IR
2.=
5m2
8422
21.E2 log
a
89
small . The various contributions are
(4rF)2 60Mit2
0 .626 GeV -4 ,
(2
2
)
1 ,
-0 .029 GeV -4 ,e 2 1
E47rJ 5 Mp4
log m,r,±
0 .807 (0 .595) GeV7 4 ,
(2)
for Z).E = 10 (20) MeV, whereas, for comparison,the authors of [7] give a value of c nv = (3 .85 +0 .60) GeV -4 , found by a fit of the 0(q 6 ) CHPTamplitude to the dato. We see therefore that the in-trinsic electromagnetic effects an the curvature arealso very small compared to the hadronie one- andtwo-loop parts and, in the analysis of ref. [7], wouldlead only to a tiny change in their LEC r ;'/2 .We now turn to the scalar form factor of the chargedand the neutral pions. For the charged pions, the re-sults are similar to the vector form factor . For neutralpions, the only effect is due to the pion mass differ-ence in the pion loops . This leads to a 2% reductionof the scalar radius of the neutral pion . We have alsofound that the scalar form factors at zero momentumtransfer are more strongly affected by isospin break-ing. Normalizing to the mass of the charged pionsleads to n,,.± (0) = m.,r ± - 0 .065 - 0.012 - 0.004) ,where the first correction is due to the electromag-netic operator ,s, C(QUQU t), i .e . the pion mass dif-ference, the second term is the well-known hadronicshift [1] (using 1 3 = 2.9), and the third term com-prises the genuine electromagnetic corrections. Toarrive at this last number, we have used the dimen-sional analysis of ref.[3] for the electromagnetic coun-terterms. Consequently, the shift due to the electro-magnetic corrections is about one third of the strongcorrection to the normalization of the charged pionsscalar form factor .
Re O, '' ° (s) (NLO)
The pion matrix elements of the energy-momentumtensor are parametrized by a scalar and a tensorform factor . For discussing electromagnetic correc-tions, one has to extend the chiral Lagrangian cou-pled to gravity in the presence of virtual photons.There is only one additional electromagnetic opera-tor at fourth order of the form
£(4 ,ern , R) k15 F2 R(QUQLTt )
( 3 )
Here, R is the curvature scalar, U encodes the pionfields, Q is the quark (or pion) charge matrix and F
is the pion decay constant (in the chiral limit) . TheLEC can at present only be estimated by di-mensional arguments . Since the energy-momentumtensor can couple directly to virtual photons, the cor-responding scalar form factor Shows a divergence atzero momentum transfer not present in the scalarform factor of the pion . Typically electromagneticcorrections are small, as shown in fig .1 for the nor-malized scalar form factor.
We conclude that the electromagnetic corrections tothe pion form factors are under control and their con-tribution to the charge and scalar radius is tiny . Thislends credit to the extraction of the pion charge ra-dius from the dato using the two-loop representationas it was performed in ref.[7] . The resulting valueis (r 2)ri = (0 .437 + 0 .016) fm 2 . This demonstratesthe usefulness of precise CHPT caIculations includ-ing electromagnetic corrections and strong isospin vi-olation.
References:
J . Gasser and H. Leutwyler, Ann. Phys. (NY)158 (1984) 142.
Ulf-G . Meißner, G . Müller, and S . Steininger,Phys . Lett . B 406 (1997) 154.
M. Knecht and R. Viech, Nucl . Phys. B 519(1998) 329.
[4] B . Kubis and Ulf-G . Meißner, hep-ph/9908261,Nucl . Phys. A, in print.
ev7r,strang
vC 7r ,photon
vCr,finiteIR
[ 1 ]
[2 ]
[3 ]
[5 ] J .F . Donoghue and H . Leutwyler, Z . Phys. C 52(1991) 343.
[6] J . Gasser and Ulf-G . Meißner, Nucl . Phys. B 357(1991) 90.
[7 ] J . Bijnens, G . Colangelo, and P. Talavera, JHEP9805 (1998) 014.
-0-040.00
0.10
020
0.30
0 :40
0.50
s''(Gev)
Figure Normalized form factor e (s) of the en-ergy-momentum tensor for charged pions . The var-ious electromagnetic corrections are shown in com-parison to the strong fourth order contribution . Thelatter is divided by a factor of 20 .
90
Construction of the chiral effective pion-nucleon Lagrangian of fourth order
N . Fettes, Ulf-G . Meißner, S . Steininger and M . MojiiS (Bratislava)
Low-energy pion and pion-nucleon physics is de-scribed in QCD via chiral perturbation theory(CHPT). This is an effective field theory designedto solve the Ward identities of the chiral symmetryof QCD order by order . CHPT is based on an effec-tive Lagrangian constructed in a systematic way interms of the asymptotically observed hadronic fieldsand consistent with all symmetries of QCD . The ef-fective Lagrangian is organized in the form of a chiralexpansion, i .e . an expansion in powers of momentaand light quark masses . At every order, the effec-tive Lagrangian contains free parameters, the so-called Iowsenergy constants (LECs) . Various quanti-ties calculated from the effective Lagrangian are re-lated by the same set of LECs entering the results.In the purely mesonic sector, the next-to-next-to-Ieading order effective Lagrangian is known . In theone-nucleon sector of CHPT, the situation is differ-ent . Here, due to the fermionic nature of the matterfields, couplings with odd powers in momenta are al-lowed and the lowest order tree graphs stein froma dimension one chiral Lagrangian . Loops start toenter at third order (in a scheme that respects thepower counting) . However, for various reasons (con-vergence, completeness, and so on) calzuladons arenow performed at the complete one-loop level, i .e . atfourth chiral order (for a review and status report,see ref .[1]) . The full effective Lagrangian is, however,only known up to third order [2] . The most generalfourth order rN chiral Lagrangian is still the miss-ing ingredient in a complete one-loop analysis withinpion-nucleon CHPT . This Lagrangian has been con-structed in ref.[3] . Most CHPT calculations for therN system (coupled to external fields) have been per-formed in the framework of Heavy Baryon CHPT(HBCHPT), a specific non-relativistic projection ofthe theory. In HBCHPT, the troublesome mass scale,the nucleon mass m, appearing in the fermion propa-gator, is simply transformed in a string of vertex cor-rections with fixed coefficients and increasing powersin 1/m. Note that the renormalization of the HB gen-erating functional at fourth order was carried out inref .[4] . However, as was pointed out recently in ref .[5],a scheme consistent with the power counting usingthe relativistic version of the irN Lagrangian can alsobe set up if one performs a different method of regu-larization . Therefore not only the heavy baryon (HB)projection of the Lagrangian is of interest . Note alsothat if one wants to match the HB approach to therelativistic theory, this is mostly easily and naturallydone starting from the relativistic approach . The re-sulting effective Lagrangian is given by a string ofterms with increasing chiral dimension,
£,),- = 49,, +
+
+ E2+ . . . , (1)
where the ellipsis denotes terms of chiral dimensionfive (or higher) . We have found that there are 118 in-
dependent dimension four operators, from which 114are in principle measurable. The other four are onlyneeded for the renormalization and accompanied byso-called high energy constants . The relativistic di-mension four Lagrangian takes the form
118£ 4)
N =
ei'Ir 0(4)
(2)i=1
and the monomials (44) are tabulated in [3] . TheHB projection leads to a much more complieated La-grangian,
69
a[i/X .D .x +h .c.
+ h .c .)
DA.D ii
+ h.c . )
( 3 )
DD,D P.v D (v D)4
- me2,,) D" + h.c.»
,
where the first sum contains the 114 low- and 4 high-energy constants in the basis of the heavy nucleonfields . V:arious additional terms appear . First, thereare the leading ?im corrections to (most of) the 118dimension four operators . These contribute to thedifference in the LECs ei and the and are tabulatedin ref.[3] . In addition, we have additional terms withfixed coefficients . They can be most compactly rep-resented by counting the number of covariant deriva-tives acting on the nucleon fields, which can be zeroto three . The corresponding (tensor) structures Wi ,
Yr, and Z,A. " are collected in various tablesin [3] . There are three other fixed coefficient termswhich are listed in the last two Enes of eq .(3).
References:
Ulf-G. Meißner, hep-ph/9711366.
N . Fettes, Ulf-G . Meißner and S. Steininger,Nucl . Phys. A640 (1998) 199.
N. Fettes, Ulf-G. Meißner, S . Steininger andM. Mojiiä, in preparation.
Ulf-G . Meißner, G. Müller and S . Steininger,hep-ph/9809446, Ann. Phys. (NY), in print.
T. Becher and H . Leutwyler, Eure Phys . J . C9(1999) 643 .
31
e i;
[1]
[ 2]
[3]
[4]
91
Virtual photons in baryon chiral perturbation theory
Ulf-G . Meißner and G . Mühe Wien)
There has been renewed interest in precisely calen-lafing electromagnetic (ein) corrections to low en-ergy strong and semi-leptonic proeesses involving the(pseudo) Goldstone bosons of the strong interactions.For example, the two loop calenlotions for elasticpion-pion scattering in the framework of chiral per-turbation theory, which is the effective field theory(EFT) of the Standard Model at low energies, havenow reached such a precision that it is mandatory toalso evaluate the pertinent dual effects of virtual pho-tons. Furthermore, to systernatically investigate theviolation of isospin symmetry one has to account forits two competing sources consistently, namely thelight quark mass difference m,, -md as well as the vir-tual photon effects . Baryon chiral perturbation the-ory offers another possibility of investigating isospinviolation . The pertinent effective Lagrangian includ-ing virtual photons and strong isospin breaking hasso far been worked out to third order, counting theelectric charge as a small parameter like the externalmomenta and quark masses [1] . lt is, however, knownthat precise and complete one loop calenlotions inthe baryon sector should be carried out to fourthorder for two reasons . First, the chiral expansion insmall momenta and meson masses proceeds in stepsof one power in the presence of baryons (unlike inthe meson sector, were only even powers in small mo-menta or meson masses are allowed for a large quarkcondensate), so that a complete one loop calenlo-tion should include terms of orders q 3 and q«whereq collectively denotes the small expansion parame-ters) . Second, it has also been shown that in manycases one loop graphs with exactly one dimensiontwo insertion are fairly large (which is related to thefact that the corresponding coupling constants en-code the leading effects due to the close-by A(1232)resonance) . These terms are of 0(q4 ) . In ref. [2], wehave considered baryon chiral perturbation theoryin the presence of virtual photons to fourth order insmall momenta q . The pertinent results of this inves-tigation can be summarized as follows:
i) We have constructed the complete fourth orderelectromagnetic Lagrangian including up to four nu-cleon (quark) Charge matrices . We have omitted allterms which only lead to an overall mass shift or cou-pling constant renormalization . Thus the completefourth order pion-nucleon Lagrangian with virtualphotons is given by (in the relativistie formulation)
5
Ffl.'t h'i e4Y .Z
90
+
F 2 hl
(e2a» ,
( 1 )ha-6
with the e2q2e4 ) monomiabs in the fields of dimen-sion four collected in ref . 2] . To be consistent with
the scaling properties of the dimension two and threeLECs, the electromagnetic LECs are multipliedwith powers of F,.,2 such that the first five LECs takedimension [mass'] while the others are of dimen-sion [mass- 1 ] . We have also worked out the corre-sponding effective Lagrangian in the heavy baryonformulation.
ii) To get an estimate of the novel electromagneticlow-energy constants, we have performed dimen-sional analysis and argued that measured in appro-priate powers of the inverse scale of chiral symme-try breaking, the h'i should be of order 1i(4rr) 2 and1/(47r) for i = 1, . . .5 and i = 6, . . .90, respectively(at a typical scale alte e .g . the mass of the p).
iii) We have evaluated the third order isospin-violating nucleon mass shift and found that itamounts to a seven percent correction of its strong(isospin-conserving) counterpart . The fourth orderelectromagnetic mass shift is tiny (as is the strongfourth order mass shift) . Note that to deal with theIR divergences stemming from the masslessness ofthe photon, we have introduced a small photon massrrhy and additional "photonic" counterterms m y2.Their effect caneels in physical observables but theseterms need to be retained in intermediate steps.
iv) The electromagnetic isospin-conserving contribu-tions to the scalar form factor of the proton (andneutron), A, = o-(2M2) cr(O), are of the order1 . . .2 MeV, i .e . not completely negligible and are thusof relevance in connecting the hinterm at the Cheng-Dashen point to its value at zero momentum trans-fer . On the other hand, all isospin-violating contri-butions to the shift from t = 2M,2 to t 0 are verysmall, only fractions of an MeV (whereas a-(0) canexhibit isospin violating effects as large as 8% [1]).
v) We have worked out the first corrections to Wein-bergs time-honored prediction for the difference ofthe S-wave scattering lengths for neutral pions offnueleons, a(ir°p) a(ir'rt) . To third order it is givenentirely in terms of the light quark mass differencerrfd m d . The fourth order corrections are small, weestimate their numerical value in the range from 4 to18%, using the dmensional analysis for the emectro-magnetic LECs developed in this work.
Reforenees:
[1] Ulf-0. Meißner and S . Steininger, Phys . Lett.B419 (1998) 403.
[2] G . Müller and Ulf-G . Meißner, Nucl . Phys. B556(1999) 265.
r(4)irN,em
92
Strange vector form factors of the nucleon
T.R. Hemmert, B . Kubis and Ulf-G . Meißner
Recently, the first results from parity-violating elec-tron scattering experiments, which allow to pin downthe so-called strange form factors of the nucleon,have become available . These strange ffs parametrizethe matrix elements of the strange vector current,(NI s IM = (NI i (A 0/3 - A°/ ) q IN) ,with q i= (u, d, s) denoting the triplet of the Iightquark fields. The singlet and octet currents areparametrized in terms of electric and magneticffs, which give the strange ffs via GE(»/M(Q 2 ) --
G » (o)+ (r2E/m,3 ) Q2/6 + 0(Q4 ) . The SAMPLE
collaboration has reported the first measurement ofthe strange magnetic form factor of the proton [1].
They give G (I:2(Q2s ) = +0.23 ± 0 .37 ± 0 .15 ± 0 .19 ,in units of nuclear magnetons at a small momen-tum transfer of Q 2s = 0.1 GeV 2 . The rather size-able error bars document the difficulty of such typeof experiment . The HAPPEX collaboration has cho-sen a different kinematics which is more sensitive tothe strange electric form facto' . [2] . Their measure-
ment implies e(Q2hr) + 0 .39 G(fi;l') (Q 2H ) = 0.023 ±0 .034 ± 0 .022 ± 0.026, at Q 2H = 0.48 GeV 2 . Ofcourse, this momentum transfer might be too highfor the chiral perturbation theory (CHPT) analy-sis at third order to hold, but in the absence ofdata at lower Q 2 , let us assume that we can stilluse the HAPPEX result . These data have been ana-lyzed in the framework of CHPT [3], extending pre-vious work [4] . lt was shown in [5] that one canmake a parameter-free prediction for the momen-tum dependence of the nucleons' strange magnetic(Sacks) form factor based on the chiral symmetry ofQCD solely. The value of the strange magnetic mo-ment, which contains an unknown low-energy cm-starrt (bo), can be deduced from the SAMPLE ex-periment using the momentum-dependence derivedin [5] . Furthermore, the SU(3) analysis of the rietetelectromagrietie form factors performed in [6] al-lows one to pin down the octet component of thestrange vector current . Thus, to leading one-loop or-der, there is only one new singlet counterterm (4 02 ),the strength of which can be determined from thevalue found by HAPPEX . This allows to give a bandfor the strange electric form factor and make a pre-diction for the MAMI A4 experiment, which intendsto measure G(;) (Q 2m) + 0 .22 GZ (Q 2 ) with a four-momentum transfer (squared) Q 2m = 0.23 GeV 2of approximately half the HAPPEX value . Underthe assumptions mentioned, one can determine theLECs bo and with sizeable uncertainties reflect-ing the experimental input . The central values areof natural size and the corresponding results for thestrange electric ff is shown in the figure by the solidlive. The dashed lines reflect the theoretical uncer-tainty based on a very conservative analysis . The
Figure 1 : Strange electric form factor of the proton.
corresponding strange radii and the strange mag-netic moment are [5, 3] : (r1 3 ) = (0 .05 ± 0 .09) fm2 ,(r2m s) -0.14 fm 2 and
fa s = (0.18 0.44) n .m. ,where the uncertainty in the strange radius stemsmostly from the uncertainty in the singlet LEC 4 02 ,whereas the prediction for the magnetic radius atthis order is parameter-free . The uncertainty in /4 is
completely given by the error of the SAMPLE anal-ysis . A few more remarks on the strange electric ffare in order . The radius is fairly small and positive.
lt is compatible with models that include irre con-tributions in the isoscalar spectral functions besidesthe vector meson poles or a dispersive analysis ofthe KK continuum . lt is also worth pointing outthat the momentum dependence of the strange elec-tric form factor is rather different from the one ofthe neutron charge form factor, which also vanishesat zero momentum transfer . We also note that usingthe central values for the LECs, the prediction forthe MAMI A4 experiment, which attempts to mea-
sure G.(2 ) (Q3j ) + 0 .22 G (M ) (Q22m) at a four-momentumtransfer (squared) of Q 22m -sm 0.23 GeV 2 , is very smallbut . icted with a large uncertainty. A more de-tailed discussion is given in ref.[3].
References:
B . Mueller et al . (SAMPLE collaboration),Phys . Rev . Lett . 78 (1997) 3824.
K.A. Aniol et al . (HAPPEX collaboration),Phys . Rev. Lett . 82 (1999) 1096.
T.R. Hemmert, B . Kubis and Ulf-G . Meißner,Phys . Rev. C 60 (1999) 045501.
M .J . Ramsey-Musolf and H . 'to, Phys . Rev . C55 (1997) 3066.
T.R. Hemmert, Ulf-G . Meißner andS. Steininger, Phys . Lett . B 437 (1998) 184.
B . Kubis, T.R. Hemmert and Ulf-G . Meißner,Phys . Lett . B 456 (1999) 240.
[2]
[3]
[4]
[5]
[ 6 ]
93
Hyperon form factors
T .R. Hemmert, B . Kubis and Ulf-G . Meißner
To third order in the chiral expansion, i .e . to lead-ing one-loop order, the electromagnetic form fac-tors (ffs) of the nucleon have been studied in chi-ral perturbation theory over the last few years . Atthat order, one has to deal with two countertermsin the electric and two in the magnetic ffs . Usinge .g. the proton and neutron electric radii and mag-netic moments as input, the ffs are fully determinedto that order . In particular, no counterterms ap-pear in the momentum expansion of the magneticffs . To this order in the chiral expansion, the ffs areprecisely described for momentum transfer squaredup to Q 2 ha 0 .2 GeV 2 . lt appears therefore naturalto extend such an investigation to the three flavorcase . Surprisingly, that has neuer been attempted un-til recently [1] despite a huge amount of studies inthree flavor chiral perturbation theory . This inves-tigation was triggered by the recent results on theE- radius reported by the WA89 collaboration atGERN and by the SELEX collaboration at FNAL(note that the SELEX results are still preliminary),
= 0.92 ± 0 .32 ± 0 .40 fm2 [2] , (r1_ ), p
0 .60 ± 0 .08 ± 0 .08 fm2 [3] , obtained by scatteringa highly boosted hyperon beam off the electroniccloud of a heavy atom (elastic hadron-electron scat-tering) . The pattern of the charge radii embodiesinformation on SU(3) breaking and the structureof the groundstate octet . In a CHPT calculationof the corresponding ffs, the baryon structure is tosome part given by the meson (pion and kaon) cloudand in part by short distance physics parametrizedin terms of local contact interactions . In the gen-eral case, such a splitting depends on the regulatorscheme and scale one chooses . Here, we work in stan-dard dimensional regularization and set A = 1 GeVthroughout (since this is the natural hadronic scale).If one performs the SU(3) calculation to third or-der, one has no new counterterms as compared tothe SU(2) case . Therefore, fixing the low-energy con-stant( (LECs) from proton and neutron propertiesallows one to make parameter-free predictions forthe hyperons. As an added bonus, kaon loops in-duce a momentum dependence in the isoscalar mag-netic form factor of the nucleon, as ferst pointedout in ref .[4], whereas in the pure SU(2) calcula-tion, Ge«Q» is simply constant . This allows oneto study the contribution of kaon loops (strangeness)to the em ffs of the nucleon . Consider now the hy-perons. Plots of the electric and magnetic ffs of thecharged and the neutral hyperons are given in ref .[1].The corresponding radii are (a more detailed discus-sion also of the neutral particles and magnetic radiiis given in [1]) (rl + ) = 0.64 . . .0 .66 fm2 , (4_ ) =0 .77 . . .0 .80 fm2 = 0 .61 . . .0 .65 fm 2 . Thegiven uncertainty does not reflect the contributionfrom higher orders, which should be calculated . The
prediction for the E- is in fair agreement with therecent measurements. The result for the E radiiis at variance with quenched lattice QCD calcula-tions, which give 0 .56(5) fm 2 and 0 .72(6) fm 2 for thenegative and positive E, respectively [5] . However,quenched lattice calculations should be taken witha grain of salt (the true error due to the quenchingis only known for very few quantities, certainly notfor the radii) . In the CHPT approach, the differenceof the radii is due to some short distance physics en-coded in the LEC [6] and to the Foldy term . Theloop contributions are almost equal, laut the differ-ence due to the counterterm and the Foldy term for
8d102the E hyperons is (4+ ) - (rln) -47,4
=
-0.10 - 0.15 fm2 , depending on how one fixesthe electric LEC and the magnetic LEC bD .Here, FF = 100 MeV is the average pseudoscalar de-cay constant . A more detailed discussion of the Pa-rameter dependence is given in [1] . All the numbersgiven here are based on a third order calculation . ltis also important to note that some of these hyperonform factors can eventually be extracted from elec-trokaonproduction data obtained at JLab . Clearly, afourth order calculation is called for to further quan-tify these results . Finally, 1 remark that the chiral de-scription of the neutron charge ff is clearly improvedin SU(3) as compared to the two flavor case . Obvi-ously, this sizeable kaon cloud effect will be reducedat next order since the effect of recoil only starts toshow up at fourth order . The inclusion of such recoileffects is expected to improve already the SU(2) cal-culation, leaving less room for the kaon cloud effects.lt is also worth pointing out that this effect fromkann loops is opposite to what one expects from a0-coupling [7] and thus some cancellations are ex-pected to Lake place.
Heferenees:
B . Kubis, T.R. Hemmert and Ulf-G . Meißner,Phys . Lett . B 456 (1999) 240.
M .I . Adamovich et al . (The WA89 Collabora-tion), Eur . Phys. 3 . C 8 (1999) 55.
1 . Eschrich (SELEX collaboration),hep-ex/9811003.
[4] T .R. Hemmert, Ulf-G. Meißner andS . Steininger, Phys . Lett . B 437 (1998) 184.
D .B . Leinweber et al ., Phys. Rev. D 43 (1991)1659.
G. Müller and Ulf-G . Meißner, Nucl . Phys . B492 (1997) 379.
M.F . Gari and W. Krümpelmann, Phys . Lett.274 (1992) 279.
[ 2 ]
[ 3]
[5]
[6]
[7]
94
Pion-nucleon scattering inside the Mandelstam triangle
P. Büttiker and Ulf-G . Meißner
A detailed understanding of elastic pion-nucleonscattering in the low energy region allows for pre-cise tests of the chiral QCD dynarnics . Recently, thisprocess has been investigated to third order in heavybaryon chiral perturbation theory by various groups.The most systematic study was performed in ref .[1],where the S- and P-wave partial wave amplitudesfrom three different analyses were used (in the phys-ical region and in the range of the lowest existingdata) to fit the low-energy constants (LECs) . How-ever, chiral perturbation theory is expected to yieldthe most reliable predictions for s (the center-of-mass energy squared) and t (the squared invariantfour-momentum transfer) lying inside the Mandel-stam triangle, for essentially two reasons . First, inthis region the scattering amplitude is purely realand it is well known that at a given order in thechiral expansion, the real part is in general moreprecisely determined than the corresponding imag-inary part (since the Iatter only starts at one looporder) . Second, in the interior of the Mandelstamtriangle the kinematical variables t and (s - u)/4rntake their smallest values . Here, rn is the nucleonmasse As this region is unphysical, there is no di-rect access by experimental data . By the use of dis-persion relations this problem can be circumvented.This is done in ref.[2] . First, using data from phaseshift analysis the pion-nucleon amplitude inside theMandelstam triangle is constructed. Then, the chi-ral third order amplitude worked out in [1] is usedto determine the nine LECs under consideration bya best fit to the dispersive amplitudes . The numeri-cal values of the LECs are compared with the onesobtained previously . One further topic needs discus-sion. lt is known that in some small regions theheavy baryon amplitude converges slowly . This canbe traced back to the fact that the strict heavybaryon limit tends to modify the analytical struc-ture of the rrN amplitude . These effects can be dealtwith by subtracting from the amplitudes the fuilBorn terms, since the latter generate the singular-ities . lt is important to stress that this subtractionprocedure is not arbitrary since the subthreshold ex-pansion of the rrN invariant amplitudes is usuallyformulated by subtracting the Born terms to avoidtheir rapid variations in the appropriate kinemati-cal variables . In ref. [2] the comparison of the irNamplitude obtained in heavy baryon chiral perturba-tion theory (HBCHPT) is done since in this frame-work the most precise predictions for the thresh-old parameters have been obtained . In that way,one can explore the consistency of these calcula-tions at the order they have been performed . Thisis the first time that the chiral rrN amplitude hasbeen considered inside the Mandelstam triangle . Afit to the dispersive amplitudes constructed from theKarlsruhe-Helsinki phase shift analysis yields the fol.-
lowing values for the LEGs : c l =- -0.81 GeV-l c28 .43 GeV -1 , c3-4 .70 GeV -1 , c4 = 3.40 GeV -1 ,
+
= 3.33 GeV -2 , d3 = -152 .3 GeV -2 , r-15-0 .11 GeV-2 , d14 -d15 = 0 .96 GeV -2 . One can alsocalculate uncertainties by assigning a global error of afew percent to the phase shifts entering the dispersiveamplitudes. Such uncertainties should, however, onlybe considered indicative . In HBCHPT the quantitiesof interest are expressed in terms of the LECs (and,of course, the contributions from the tree and loopgraphs. These are, however, free of unknown paräme-ters .) . The data set given above yields e .g . the follow-ing predictions for some of the Iow subthreshold co-efficients aas = -1 .32 M- 1 , = 4.49 M-3 ,aal =0.97 M- 3 ,boo as- 9.99 M', with M 139 .57 MeVthe charged pion mass . The subthreshold parametersare in good agreement with the Karlsruhe analysis,a3-0 = -1 .46 + 0 .10, dto = 4.66, 4 = 1 .14 + 0 .02and bo-0 = 10.36, in appropriate units of the inversepion mass . Of particular interest is the result for dito ,which came out consistently too large in the chiralanalysis based on the phase shifts, cf . table E.1 inref.[1] . bo-o, on the other hand, is still not in agree-ment with the Karlsruhe analysis . This is not surpris-ing: the chiral representation of the isovector spin-flip amplitudes h- (v 0, t) has only one free Param-eter, c4 . Therefore, there is not enough fiexibility toobtain a satisfactory fit to the dispersive counter-part . Most striking, however, is the result for thepion-nucleon a--term, cr(0) 40 MeV, which agreesperfectly with the dispersion theoretical analysis ofref.[3], cr(0) st= (44 ± 8 ± 7) MeV, which is also basedon the Karlsruhe phase shifts . On the other hand,the third order chiral perturbation theory analysesbased on the phase shifts lead to much larger val-ues of the sigma-term, o-(0)
70 MeV in ref.[1] forthe corresponding central values of the LEC Thislends further credit to the statement that the chi-ral predictions for rsN scattering are most reliableinside the Mandelstam triangle since there the per-tinent kinematical variables take their smallest pos-sible values . What remains to be done is to supplytheoretical uncertainties and work out the results formore modern phase shift analysis, like e .g . from theVPI/GWU group.
Refehenees:
[1] N . Fettes, Ulf-G . Meißner and S . Steininger,Nucl . Phys. A 640 (1998) 199.
[2] P. Büttiker and Ulf' G . Meißner,bep-ph/9908247, Nucl . Phys. A, in print.
[ 3] J . Gasser, H . Leutwyler and M .E . Sainio, Phys.Lett . B 253 (1991) 252.
95
Chiral unitary pion-nucleon dynamics in the presence of resanances
Ulf-G . Meißner and J .A . Oller
There are many reasons why it is interesting to studypion-nucleon scattering . First, in the threshold re-gion, chiral perturbation theory is applicable andthus the chiral structure of QCD can be investigated.This very precise method is, however, only applica-ble in the threshold and in the unphysical regionsince there the pion momenta are small . At higherenergies, additional physics due to the appearanceof resonances and coupled channel effects sets in.This region can either be treated using dispersionrelations or meson-exchange type models . While allthese models in general give a good description ofthe phase shifts (and inelasticities), they are not in-cluding the pion loops resulting from the chiral struc-ture of QCD in a systematic fashion (the often em-ployed unitarization schemes or resummation tech-niques include some classes of these diagrams, butnot all) . Furthermore, in these references most of thetree level diagrams involving the exchange of mesonresonances do not have the momentum dependencerequired by chiral symmetry. Consequently, it wouldbe interesting to devise a scheme that at low ener-gies exactly reproduces the chiral perturbation the-ory amplitudes (to a given order in the chiral ex-pansion) but also allows one to work in the reso-nance region, including also resonance exchange attree level in conformity with the non-linearly re-alized chiral symmetry. Such an approach was de-veloped in ref.[1] . lt is similar to the one set up inref. [2] for meson-meson scattering . lt is a novel ap-proach to chiral unitary meson-baryon dynamics inthe presence of resonances . As a first application, wehave considered elastic pion-nucleon scattering fromthreshold up to the opening of the inelastic chan-nels at center-of-mass energies W 1 .3 GeV . Makinguse of the time-honored N/D method, we have de-rived the most general structure of any pion-nucleonpartial wave amplitude neglecting unphysical cuts.The latter are then treated in a perturbative chiralloop expansion based on the power counting of heavybaryon chiral perturbation theory. The most impor-tant and novel features and results of this approachcan be summarized as follows:
i) The approach is based on subtracted dispersionrelations and is by construction relativistic . No formfactors, finite momentum cut-offs or regulator func-tions are needed to render the resummation finite.This is done by a subtraction of the dispersion rela-tions below the physical threshold.
ii) The amplitude is matched to the one of (heavybaryon) chiral perturbation theory (HBCHPT) atthird order [3] . This is done at an energy slightlybelow the physical threshold . In this region, theHBCHPT amplitude is expected to converge . Also,for such energies the pertinent subtraction constantis real . lt is straightforward to extend this matching
to a fourth order and/or a relativistic CHPT ampli-tude.
iii) The explicit resonance degrees of freedom con-tain free parameters (couplings and masses) whichare determined from a best fit to the pion-nucleonpartial waves . Some of these parameters, in particu-lar the ones of the are very well determined . Forexample, the pole of the ,A in the complex energyplane is located at (m ,‘1, , FA /2) = (1210,53) MeV.We also find grZIN = 2.05 dose to the spie-isopsinSU(4) (or Iarge prediction of 2 .01 . Couplings ofthe scalar and vector mesons can be pinned down lessprecisely . We have also pointed out a new coupling ofthe p not considered in conventional schemes [4] . Ourapproach is consistent with the concept of resonancesaturation of the low-energy constants.
iv) The pion-nucleon phase shifts are well describedbelow the onset of inelasticities . In particular, theP33 and Pll partial waves are very accurately repro-duced . With the exception of the isoscalar S-wavescattering lengths, we also find a reasonable descrip-tion of the trN S- and P-wave scattering lengths andvolumes . This can be improved by matching to amore precise (HB)CHPT amplitude.
v) Our method is very general . lt embodies (as a par-ticular limiting case) the inverse amplitude method(IAM) recently applied to the zrN scattering . The chi-ral unitary approach [5], based on the lowest ordertree level meson-baryon interactions, appears also asa special case.
vi) The extension of this approach to coupled chan-nels (like rrN -+ i7N) and to the three-flavor sector(with coupled channels) is in principle straightfor-ward . For the kaon-nucleon system, the matchingto the chiral perturbation theory amplitude is moretricky due to the appearance of subthreshold reso-nances, like e .g . the A(1405) . Work along these linesis in progress.
Reforenees:
Ulf-G . Meißner and J .A. Oller,hucl-th/9912026.
[2] J . A. Oller and E. Oset, Phys . Rev . D60 (1999)074023.
N. Fettes, Ulf-G . Meißner and S . Steininger,Nucl . Phys . A640 (1998) 199.
B . Borasoy and Ulf-G . Meißner, Int . J . Mod.Phys . All (1996) 5183.
E . Oset and A . Ramos, Nucl . Phys. A635 (1998)99.
[3 ]
[4]
[5 ]
96
One-Ioop analysis of the reaction irN -ei. zrzrN
V. Bernard (Strasbourg), N. Fettes and Ulf-G . Meißner
Single pion production off nucleons has been at theDeiner of numerous experimental and theoretical in-vestigations for many years . One of the original mo-tivations of these works was the Observation that theelusive pion-pion threshold S-wave interaction couldbe deduced from the pion-pole graph contribution ofthe pion production reaction. A whole series of preci-sion experiments at PST, Los Alamos, TRIUMF andCERN (and other laboratories) has been performedover the last decade and there is still on-going ac-tivity . On the theoretical side, chiral perturbationtheory has emerged as a precision tool in low en-ergy hadron physics . lt not only allows to investigatelow-energy pion-pion scattering to high accuracy,laut also elastic pion-nucleon scattering and inelas-tic pion production can be studied in the thresholdregion. Another important aspect of inelastic pionproduction is the excitation of resonances, some ofwhich couple much stronger to the irirN final-statethan to the pion-nucleon continuum. In what fol-lows, we will be concerned with the low energy re-gion which allows to address questions connected tothe chiral structure of QCD.We have performed a complete third order calcula-tion of the reaction rrN es. rrnN in heavy baryonchiral perturbation theory [1] based on the minimalLagrangian developed in ref .[2] . We had to consider26 different tree graphs and 49 one loop topologies.Note that the tree contributions with fixed coeffi-cients are obtained from the 1/m expansion of therelativistic amplitudes . The pertinent results of thisinvestigation can be summarized as follows:
i) We have used the total cross sections in all fivephysical channels (for 2', < 250 MeV, with thekinetic energy of the incoming pion in the labora-tory frame) and the older double differential crosssections d 2er/d9dT for the process ir - p -+ ir+ir- n tofit the six new dimension three LECs . The other fourdimension two and five (combinations of) dimensionthree LECs were taken from the study of elastic rrNscattering in ref .[2] . We observe that the values oftwo pairs of these LECs are almost perfectly anticor-related, so that only four LECs can be determined.They come out of natural size.
ii) Using this input, we predict the total cross sec-tions for energies up to 7; = 400 MeV . We find anexcellent description of the rr~p tr + ir- n channelwhereas the largest deviations are seen for the pro-cess ir+p -+ ir + ir+ n. The angular correlation func-tions for 7r -p ir+ir-n can be satisfactorily re-produced, with the exception of the small 8 2 an-gles. In addition, most of the recent TRIUMF dataon du/dM, , dcr/di de /d cos 9 and d2oldtd4i, canalso be reproduced.
iii) At third order, the contribution from the loopgraphs is essentially negligible . Unitarity corrections
therefore play no role . This allows one to understandwhy resonance modeln work fairly well even in thethreshold region (although these are not as preciseas the caleulation presented here) . The effedt of theterms proportional to the dimension three LECs issomewhat more pronounced . By far the largest con-tribution at this order comes from the 1/m correc-tions to the dimension two LECs e i and the 1/m2corrections with fixed coefficients . This together withthe smallness of the loop contributions explains whythe tree caIculation in ref.[3] works so well . lt alsomeans that by far the most important terms arethe pion-nucleon subgraphs with an additional pionadded in all possible topologies.
iv) We now consider briefiy the threshold ampli-tudes V1 , 2, as defined in ref.[4] . If we convert ourcentral values and errors of the corresponding LECsdi (i � 18) into the contribution to 7) 1,2 , we findDa' _ (0 .27±0.07) fm3 , V 2d ‘ = (-1 .60±0 .15) fm.3which is within 1 .5 er of the result of ref.[4] based onRoper excitation, l)r (-0.40 ± 0 .90) fm 3 . In ad-dition, we have a smaller contribution to 7), whichis however of the saure size as the other contributionsform the loops, ei and the terms.
v) Our study is based on the standard scenario ofchiral symmetry breaking where a quark mass In-sertion is counted as second order in the chiral ex-pansion. This reflects itself in the natural size of themesonic LECs i1, 2 , 34 used here . The generalized sce-nario with m q O(q) can be modeled by setting13 st -70 . Keeping all other mesonic and baryonicLECs fixed, we have studied the sensitivity of thetotal and differential cross sections as well as theangular correlation functions to the value of £3 . Weconclude that one is not able to pin down the LECi3 with suffizient accuracy to discriminate betweenthe two scenarios of chiral symmetry breaking byjust comparing the observables directly with chiralanalysis (which is of course different from applyingChew-Low techniques).
A fourth order study is needed to further sharpenthese statements.
References:
[1] N. Fettes, V . Bernard and Ulf-G. Meißner,hep-ph/9907276, Nach Phys . A, in print.
[2] N . Fettes, Ulf-G. Meißner and S. Steininger,Nucl . Phys . A 640 (1998) 199.
[3] V . Bernard, N . Kaiser, and Ulf-G . Meißner,Nucl . Phys . A619 (1997) 261.
[4] V . Bernard, N . Kaiser, and UWG . Meißner,Nucl . Phys . B457 (1995) 147.
97
The nucleon-nucleon interaction &cbm effective field theory
E. Epelbaum, W. Glöckle (Bochum) and Ulf-G . Meißner
Over the last years, effective field theory methodshave been used to gain a better understanding of thetwo-nucleon interaction at low and intermediate en-ergies . While at present these stndies do not aim atsubstituting the highly successful "realistic" poten-tials build from meson exchanges (like the e .g . Bonn-Jülich, Nijmegen, Argonne or RuhrPot potential),effective field theory (EFT) allows for a systerrintieand controlled expansion of observables in systemswith two or more nudeons. Apart from dealing withthe various scales appearing in nuclear systems, it isstraightforward to implement the spontaneously andexplicitely broken chiral symmetry of QCD as well asexternal probes in the EFT. The appearance of shal-low bound states (or, equivalently, large scatteringlengths) requires some method of resummation . Oneapproach of doing this resummation is to build thepotential from EFT and employ it in a properly regu-larized Lippmann-Schwinger (or Schrödinger) equa-tion as proposed by Weinberg [1] and extended byus in ref.[2] . Within this framework, we have calcu-lated properties of the two-nucleon System based ona chiral effective field theory [3] . The results of thisinvestigation can be summarized as follows:
1) Based on a modified Weinberg power counting(as explained in ref.[2]), we have constructed a chi-ral two-nucleon potential at NNLO . lt consists ofone- and all two-pion exchange diagrams, includ-ing dimension two insertions from the effective pion-nucleon Lagrangian . The corresponding LECs havebeen taken from an investigation of nN scatter-ing [4] . In particular, the so-called football and tri-angle graphs are a direct consequence of the non-linearly realized chiral symmetry . In addition, thereare two and seven four-nucleon contact interactionsat LO and NLO, respectively . The coupling constantsof these terms must be fixed by a fit to data.
2) For large momenta, the potential becomes unphys-ical and has to be regularized . We perform this reg-ularization on the levei of the Lippmann-Schwingerequation, using either a sharp or an exponential reg-ulator function . At NLO, physics does not depend onthe cut-off in the range between 400 and 650 MeV.At NNLO, this range is larger and extends from 650to 1000 MeV. This can be understood from the chi-ral TPEP, which at NNLO includes 'rar correlations.These introduce a new mass scale well above twicethe pion mass.
3) We have shown that the contact interactions canbe combined in such a way that each combinationfeeds into one partial wave . More precisely, the einefour-nucleon couplings can be determined uniquelyby a fit to the two S-waves, four P-waves and themixing parameter e i for nucleon laboratory energiesbelow 100 MeV . As expected from the power count-ing underlying the EFT, the fits improve when going
from LO to NLO to NNLO.
4) At NNLO, the resulting S-waves are of veryhigh precision (for nucleon laboratory energies below300 MeV), see e .g . fig . 1 . The so-called range pa-rameters agree with what is found in the phase shiftanalysis . The P-waves are mostly well described, inparticular the mixing parameter is in good agree-ment with the phase shift analysis . We also note thatabove nucleon cms momenta of about 150 MeV, ourNLO and NNLO results are far better than the oneobtained in the KSW scheine [5] at NLO and NNLO,see fig .2 .
Ist)
Figure 1 : Predictions for the l S0 phase shift (in desgrees) for nucleon laboratory energies E iab below300 MeV (0 .3 GeV) . The dotted, dashed and solidcurves represent LO, NLO and NNLO results, in or-der . The squares depict the Nijmegen PSA results.
Figure Predictions for the mixing parameter e ifor nucleon cms momenta p below 350 MeV . Theshort-dashed, Jong-dashed and solid curves repre-sent our LO, NLO and NNLO results, in order . Forcomparison, the NLO and NNLO results in the KSWscheme are also shown. The filled squares depict theNijmegen PSA results.
5) All other partial waves are free of Parameters . TheD-waves, in particular 3D1 (see fig .3) and 3D3 arevery well described . We have also discussed the cut-off sensitivity of these results . The NNLO TPEP is
• Nijmegen PSANNLO
- NLO LO
- NNLO (KSW)NLO (KSW)
98
too strong in the triplet F-waves. This is expected tobe cured at N 3 LO due to the appearance of dimen-sion four contact terms . For the peripheral waves, werecover the results of the Munich group [6], namelythat in most cases OPE works well but chiral NNLOTPEP clearly improves the description of some par-tial waves like e .g . 3G 5 , 3H 5 or 3 17 .
301
Figure 3 : Predictions for the3 Di phase shift (in de-grees) for nucleon laboratory energies Etab below300 MeV (0 .3 GeV) . The dotted, dashed and solidcurves represent LO, NLO and NNLO results, in or-der . The squares depict the Nijmegen PSA results.
6) The deuteron properties are mostly well described,at NLO and NNLO, compare table 1 . In particular,the binding energy, which is not used in the fittingprocedure, and the matter root-mean-square are inexcellent agreement with the data . As in all mod-ern potentials, the quadrupole moment comes outtoo small (note that the mesn-exchange current con-tribution has not yet been calculated) . At NNLO,the deuteron wave functions shows some interestingstructure due to the appearance of two very deeplybound states . These are an artefact of the NNLOapproximation . They have no influence an low en-ergy properties and can be completely projected outfrom the theory. A comparison with the CD-Bonnwave functions is shown in fig .4 .Our precise deuteronwavefunctions can be used for pion photoproduction,pion-deuteron scattering or Compton scattering offdeuterium.
NNLO NNLO-A Exp.
Ed [MeV] -2.2238 -2.1849 -2.224575(9)Qd [fm 0.262 0.268 0.2859(3)
0.0245 0.0247 0.0256(4)rd [frn] 1 .967 1.970 1.9671(6)
A s [fm-tr2 ] 0.884 0.873 46(16P5 [%] 6.11 5 .00
Table 1 : Deuteron properties derived from our chiralpotential at NNLO in comparsion to the data. Ihre,rd is the root-mean-square matter radius.
7) We have also considered an approach with explicitd degrees of freedom in the TPEP. This NNLO-Aapproach is very similar to the NNLO results in thetheory without isobars, with the exception of the par-tial waves that are sensitive to pionic scalar-isoscalar
-0 .3 10
2
4
8
10
r [fit]
Figure 4 : Coordinate space representations of the S-(upper panel) and D-wave (lower panel) deuteronwave functions at NNLO compared to the one fromthe CD-Bonn potential.
correlations like e .g . 3D3 . We conclude that the inclu-sion of the A via resonance saturation of the dimen-sion two rrN LECs captures the essential physics ofthe isobar in the two-nucleon system. We note, how-ever, that a more systematic study of pion-nucleonscattering in an EFT including the A is needed tofurther quantify these statements.
Our findings do not only show that the scheme orig-inally proposed by Weinberg works quantitatively,it even works much better than it was expected . ltextends the succesfull applications of effective fieldtheory (chiral perturbation theory) in the pion andpion-nucleon sectors to systems with more than onenucleon . Clearly, one should now reconsider pro-cesses, which have been evaluated using Weinberg'shybrid approach (r - d scattering, -yd yd -
yd), reconsider the questions surrounding isospin vi-olqtion in the NN interaction and extend these con-siderations to systems with more than two nucle-ons . In particular within this scheme we can generatethe most general three-nucleon force. With that, wehope to resolve the longstanding so-called A y puzzlein elastic low-energy neutron-deuteron scattering.
References:
S . Weinberg, Nucl . Phys. B363 (1991) 3.
E . Epelbaoum, W . Glöckle and Ulf-G . Meißner,Nucl . Phys. A637 (1998) 107.E . Epelbaoum, W . Glöckle and Ulf-G . Meißner,nucl-th/9910064, Nucl . Phys. A, in print.P. Büttiker and Ulf-G . Meißner,hep-ph/9908247, Nucl . Phys. A, in print.
D .B . Kaplan, M.J. Savage and M .B. Wise, Nucl.Phys . B534 (1998) 329.
[6] N. Kaiser, R . Brockmann and W . Weise, Nucl.Phys . A625 (1997) 758.
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99
Isospin violation in the nucleon-nucleon interaction
E. Epelbaum and Ulf-G . Meißner
lt is well established that the nucleon-nucleon inter-action is charge dependent . For example, in the 1 S0channel one has for the scattering lengths a and theeffective ranges r (n and p refers to the neutron andthe proton, in order) Aac 1B
(an, app ) - anp5 .7 ± 0 .3 fm , Arc 1B (rnn + rpp ) rnp 0 .05 ±0 .08 fm . These numbers for charge independencebreaking (CM) are based an the Nijmegen poten-tial and the Coulomb effect for pp seattering is sub-tracted based an standard methods . The charge inde-pendence breaking in the scattering lengths is large,of the order of 25%, since anp = (-23 .714±0.013) fm.In addition, there are charge symrnetry breaking(CSB) effects leading to different values for the ppand nn threshold parameters, zlacsB = app - am, =1 .5 ± 0.5 fm , dress =rpp -rnn 0 .10 ± 0 .12 fm .Within QCD, CSB and CIB are of course due tothe different masses and charges of the up and downquarks. Such isospin violating effects can be system-atically analyzed within the framework of chiral ef-fective field theories . In the two-nucleon sector, acomplication arises due to the unnaturally large S-wave scattering lengths . One method to deal withthis the recently proposed power divergence sub-traction scheme (PDS) of Kaplan, Savage and Wise(KSW) [1] . Essentially, one resums the lowest orderlocal four-nucleon contact terms h, Co(Nt lV)«inthe S-waves) to generate the large scattering lengthsand treats the remaining effects perturbatively, inparticular also pion exchange . This means that mostlow-energy observables are dominated by contact in-teractions. The chiral expansion for NN scatteringentails a new scale ANN of the order of 300 MeV, sothat one can systematically treat external momentaup to the size of the pion mass . In this context, it isinteresting to study CIB (or in general isospin viola-tion) which is believed to be dominated by long rangepion effects . That is done in ref.[2] . First, we writedown the leading strong and electromagnetic four-nucleon contact terms . lt is important to note thatin contrast to the pion or pion-nucleon sector, onecan not easily lump the expansion in small momentaand the electromagnetic coupling into one expansionbut rather has to treat them separately. Then weconsider in detail CIB . The leading effect starts outat order aQ', where Q is the generic expansion pa-rameter in the KSW approach and a 1/137 is thefine structure constant . lt stems from OPE plus acontact term of order a with a coefficient of naturalsize that scales as Q -2 . Similarly, the leading CSBeffect are four-nucleon contact terms of order a andorder -md , which also scale as Q- 2 . While in thecase of 4 11 this scaling property is enforced by a can-cellation of a divergence, the situation is a priori dif-ferent for CSB . however, for a consistent counting ofall isospin breaking effects related to strong or em in-
sertions, one should count the quark mass differenceand virtual photon effects similarly. Note, however,that these CIB and CSB terms are numerically muchsmaller than the leading strong contributions whichscale as Q- l because a 1 and (rnn rn d )/Ax « 1(with A x the typical hadronic scale of about 1 GeV).
The corresponding constants, which we call 4 1 ' 21 ,together with the strong parameters (as given in thework of KSW) can be determined by fitting the therescattering lengths app , ann, anp and the np effectiverange . That allows to predict the momentum depen-dence of the np and the nn 1 S0 phase shifts, as shownin the figure below.
Figure 1 : 1 So phase shifts for the np (dashed line)and nn (solid line) systems versus the nucleon cmsmomentum. The emipirical values for the np case(open squares) are taken from the Nijmegen analysis.The open octagons are the nn "data" based an theArgonne V18 potential.
Based an these observation, we can in addition give ageneral classification for the relevant operators con-tributing to CM and CSB in this scheme . All lead-ing, next-to-leading and next-to-next-leading or-der terms in powers of a and Q have been workedout . This classification scheme explains the observa-tion why a possible charge dependence in the pion-nucleon couplings plays no role in CIB and also themuch debated w-y-exchange is suppressed by two or-ders in the EFT expansion [3] . lt would be interestingto extend this formalism to other partial waves andto higher energies so as to investigate e .g . isospin vi-olation in pion production.
Referenees:
D .B . Kaplan, M .J . Savage and M .B. Wise, Phys.Bett . B424 (1999) 329 ; Nucl . Phys. B534 (1998)329.
E. Epelbaum and Ulf-G . Meißner, Phys . Bett.B461 (1999) 287.
E. Egelbaum and Ulf-G . Meißner,nucl-th/9903046.
[ 2]
[3 ]
100
Nucleon properties and the NN interaction in a chiral rrpwo- model
Ulf-G . Meißner, A . Rakhimov (Tashkent), U . Yakhsiev (Tashkent)
In ref .[1] Furnstahl, Tang and Serot (FTS) proposeda new model for nuclear matter and finite nuclei thatrealizes QCD symmetries such as chiral symmetry,broken scale invariance and the phenomenology ofvector meson dominance . An important feature ofthis approach is the indusion of light scalar degrees offreedom, which are given an anomalous scale dimen-sion . The vacuum dynamics of QCD is constrained bythe trace anomaly and related low-energy theoremsof QCD. The scalar-isoscalar sector of the theory isdivided into a low mass part that is adequately de-seribed by a scalar meson (quarkonium) and a highmass part (gluonium), that can be "integrated out",leading to various couplings among the remainingfields . The application of the model to the proper-ties of nuclear matter as well as finite nuclei gavea satisfactory description . Further developments ofthe model showed that the light scalar related to thetrace anomaly can play a significant role not onlyin the description of bound nueleons but also in thedescription of heavy-ion collisions .It was also shownthat the anomalous cannot be due to an effect ofnuclear density on the trace anomaly of QCD . Herea natural question arises : What is the role of thislight quarkonium in the description of the propertiesof a single nucleon, when it is taken into account intopological nonlinear chiral soliton models, which aresimilar to the FTS effective Lagrangian on the singlenucleon level? We have introduced a dilaton field intothe rspw-model [2] and investigate some properties ofsingle nucleons which emerge as solitons in the sec-tor with baryon number one (B = 1) as well as theNN interaction [3] . The model has only two unknownparameters, to, and f, . We use m,r = 550 (720)MeVand = 242 MeV as given in [1] . These values leadto a gluon condensate c 1 / 4 = 260 . . .300 MeV, whichis consistent with sum rule determinations.
First, we consider the infiuence of the light scalar-isoscalar meson on the single nucleon properties.These are essentially unchanged apart from an im-provement in the axial-vector coupling constant g A .
Same typical results are : (r 2E)p1/2 = 0 .94 (0 .86 ±0 .01) fm, (ri) n = -0.16 (-0 .119 ± 0 .004) fm 2 ,,u p / p n = -1 .30 (-1 .46) and gA = 0.95 (1 .26) (theempirical numbers are given in the brackets).
Second, we study the meson-nucleon form fcators,including also a non-trivial metric MT � 1 [4] . Infact, a monopole approximation at small q 2 = t of thenormalised form factor G'(t)/G" (0) sr, A,2/(A,2, - t)gives A, = 860 MeV and A, = 1100 MeV for MT =-1 and MT � 1 respectively, compared to its emperi-cal fit, ABE = 1300 MeV Note that our results forA . are in line with recent coupled-channel calzula-tions of the Jülich group [5] . There, a monopole formfactor with A, - 800 MeV is obtained . Second, thevalue for g o- NN and the cut-off parameter of sigma
-nucleon vertex are smaller than their OBE pre-diction A BE s,- 1300 2000 MeV . One can concludethat the present model gives a softer oNN form fac-tor than is obtained by OBE . As it had been noticedbefore, the t-plane for each form factor has a cutalong the positive real axis extending from t = to todo . The cut for the a-nucleon vertex function startsat to = 4rn, 2, reflecting the kinematical threshold forthe er -4 7C7r channel.Third, once the vertex function of the correspondingmeson-nucleon interaction has been found, its ap-propriate contribution to the NN interaction maybe easily calculated by using well known techniquesfrom OBE. The detailed formulas are given else-where [6] . In particular, the contribution of the o--meson exchange to the central potential is given by
" k2dk G,,. NN (k2 ) jo(kr)Vo.(r) =
( 1 )
fo
2 7r2 k2 m20,
The central NN potential in the T = 0, S = 1 state(the deuteron state) is presented in Fig . 3 of ref.[3] incomparison with the Paris potential . Our predictionis in good agreement with the emperical one . Notethat the desired attraction in the central VNN hasbefore been obtained in the rrpcv model by means oftwo-meson exchange [6].To summarize, we have developed a topologieal chiralsoliton model with an explicit light scalar-isoscalarmeson field, which plays a central role in nuclearphysics, based on the chiral symmetry and brokenscale invariance of QCD. We have shown that forthe single nucleon properties, the successfull descrip-tion of the electromagnetic observables of the 7r/3Wmodel is not modified and even the value for theaxial-vector coupling is somewhat improved. In thetwo-nucleon sector, this extended rrgwo- Lagrangianleads to the correct intermediate range attraction inthe central potential and a soft uNN form factor forboth values of sigma meson mass na, = 550 MeVand m,,. = 720 MeV.
Referenees:
R .J . Furnstahl, H . Tang and B . Serot, Phys.Rev. C52 (1995) 1368.
Ulf-G . Meißner, Phys . Rep . 161 (1988) 213.
Ulf-G . Meißner, A . Rakhimov and U . Yakhshiev,nucl-th/9901067, Phys . Lett . B, in print.
[4] G . Holzwarth, G . Pari and B . Jennings, Nucl.Phys . A515 (1990) 665.
[5 ] R . Böckmann et al ., Phys. Rev . C60 (1999)055212.
[6] N . Kaiser and Ulf-G . Meißner, Nucl . Phys . A506(1990) 417.
[ 1 ]
[3]
101
Neutral pion electroproduction off deuterium at threshold
V . Bernard (Strasbourg), H . Krebs, Ulf-G . Meißner
Chiral perturbation theory has been successfully ap-plied to neutral pion photo- and electroproductionoff the proton as well as to Ir0 photoproduction on thedeuteron [1] . The scattering off deuterium is not onlyinteresting per se, but also because this loosely boundtwo-nucleon system can be used as a neutron target.In particular, in ref.[1] it was shown that one can in-deed extract the elementary ir0 n production ampli-tude from a precise measurement on the deuteron.Furthermore, at MAMI experiments for neutral pionelectroproduction off deuterium at small photon vir-tualities have been untertaken and are presently be-ing analyzed . Here, we can report on first results forthis process obtained in chiral perturbation theoryto third order [2] . We use the methodology devel-oped by Weinberg, which relates scattering processesinvolving a single nucleon to nuclear scattering pro-eesses . The non-perturbative effects responsible fornuclear binding are accounted for using phenomeno-logical nuclear wavefunctions. Although this clearlyintroduces an inevitable model dependence, one cancompute matrix elements using a variety of wave-functions in order to ascertain the theoretical errorinduced by the off-shell behavior of different wave-functions . Here, we work to third order in the chi-ral expansion and consider only threshold kinemat-ics (i .e . the pion is produced at rest) and thus calcu-late the pertinent transverse and longitudinal S-wavemultipoles . White a third order computation is notsufficient for the normalization of the elementary am-plitudes, the explicit calculations for rr 0 electropro-duction off the proton and rr 0 photoproduction offthe deuteron to fourth order lets one expect that themomentum dependence of the S-wave cross section issufficiently accurately described at the order we areworking . To third order (O(q», where q denotes asmall momentum or a pion mass) in chiral perturba-tion the S-wave neutral pion electroproduc-tion amplitude off the deuteron can be decomposedas follows :
msd s + mtdb
2Ed f
2(Ld E d ) J
, (1)
where f is the deuteron angular momentum vector,and and k are the polarization vector and (direc-tion of the) three-momentum of the virtual photon,respectively . Note that in electron scattering k 2 < 0.The electric dipole amplitude Ed characterizes thetransverse response whereas Ld parametrizes the lon-gitudinal response of the deuteron to the virtual pho-ton. In general, the multipoles depend on the photonvirtuality k 2 and the pion energy w . Since we onlyconsider the production threshold Wthr = .lV40 , wewill not further specify this dependence . The corre-sponding amplitude obtain contributions from singlescattering (ss) as well as the so-called three-body
(tb) graphs, see fig,l . The 0(q3) results for Ed and
ss
tb,a
tb,b
Figure 1 : Single scattering (ss) and three-body (tb)interactions which contribute to neutral pion electro-production at threshold to order q3 (in the Coulombgauge) . The solid, dashed and wiggly lines denotenucleons, pions and photons, in order . The deuteronwavefunction is symbolized by the triangle.
Ld are shown in fig . 2 . In both cases, the three-bodycontribution is sizeable . As in the case of photopro-duction, graph (tb,a) (cf. fig . 1) totally dominatesthe electric dipole amplitude. This is different for thelongitudinal response, where the contribution fromgraph (tb,b) is smaller than the one of graph (tb,a)but of comparable magnitude . We observe that bothEd and Ld vary significantly with increasing 1k 2 1 . Asillustrated by the dotted lines in fig . 3, which havebeen obtained by a constant shift of the tr 0 n ampli-tude by *l x 10- 3/M,+, there is some sensitivity tothe elementary scattering off the neutron . Calcula-tions of the S-wave cross section are also presentedin [2] and extensions to fourth order and kinematicsabove threshold are under way.
3 .00 !
0 .00
ä-0 -1 .00
--7 -2 .00
Figure 2 : S-wave multipoles of the deuteron . In theupper and lower panel, the electric dipole and thelongitudinal (scalar) multipoles are shown, respec-tively, by the solid lines . The dot-dashed line is thesingle scattering contribution.
References:
[1] S.R. Beane, V. Bernard, T .-S.H. Lee, Ulf-G . Meißner and U . van Kolck, Nucl . Phys . A618,381 (1997).
[2] V. Bernard, H. Krebs and Ulf-G . Meißner,nucl-th/9912033.
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102
Dense QCD : Overhauser or BCS Bairing ?
B .-Y . Park (Taejon), M . Rho (Saclay), A. Wirzba and I . Zahed (Stony Brook)
Quantum chromodynamics (QCD) at high density,relevant to the physics of the early universe, compactstars and relativistic heavy ion collisions, is presentlyattracting a renewed attention from both nuclear andparticle theorists . Following an early suggestion byBailin and Love [1], it was recently stressed that atlarge quark density, diquarks could condense into acolor superconductor [2].At large density, quarks at the edge of the Fermisurface interact weakly thanks to asymptotic free-dom . However, the high degeneracy of the Fermi sur-face causes perturbation theory to fall . Thus parti-des can pair and condense at the edge of the Fermisurface leading to energy gaps . Particle-particle andhole-hole pairing (BCS effect) have been extensivelystudied recently [2] . However, particle-hole pairing atthe opposite edges of the Fermi surface (Overhausereffect) [3] has received little attention with the ex-ception of an early variational study in Ref . [4] for alarge number of colors Ne , and a recent renormaliza-tion group argument in [5].In Ref. [6] we have constructed an effective actionfor the various scalar-isoscalar excitations around theFermi surface and have shown that in dense QCD,the equations that drive the particle-hole instabil-ity at the opposite edge of a Fermi surface resem-ble Chose that drive the particle-particle or hole-holeinstability in the scalar-isoscalar channel, modulophasesspace factors . Our analysis in the decoupledmode shows that in weak-coupling, the Overhausereffect can overtake the BCS effect only at large Nein the scalar-isoscalar channel, in agreement witha recent renormalization group result [5] . The BCSpairing is more robust to screening than the Over-hauser pairing in weak coupling . In strong coupling,the Overhauser effect appears to be comparable tothe BCS effect, especially if multiple standing wavesare used, allowing for further cooperative pairing be-tween adjacent patches on the Fermi surface . This isparticularly relevant for pairings with large energygaps which are expected to take place at a few timesnuclear matter density [7].Our effective action is well suited to the use of vari-ational approximations and leads naturally to ex-act integral equations by variations, especially in thepresence of interactions with retardation and screen-ing . lt would be interesting to repeat our analysis atnonasymptotic densities using instanton-generatedvertices to address the Overhauser effect . Indeed,for instantons the cutoff is fixed from the onset bytheir inverse size . As we have shown in [6], the Over-hauser pairing, much like the BCS pairing by mag-netic forces [8], relies on scattering between pairsin the forward direction that is kinematically sup-pressed in the transverse directions (in fact exponen-tially suppressed [4]) . Since the instanton interactionis nearly uniform over the Fermi sphere, we expect a
geometrical enhancement in the BCS pairing in com-parison to the Overhauser pairing . We recall that inthe Iatter the interaction is enhanced by a factor oforder Ne . Which one dominates at a few times nu-clear matter density and
= 3 is not clear a priori.Instantons in the vacuum crystallize for > 20 [9]in the quenched approximation, and 3 < Ne < 20in the unquenched case. The crystallization is likelyto be favored by finite /1 as the quarks are forced toline-up along the forward x 4 -direction.lt is amusing to note that the crystal phase Breakscolor, flavor, and translational symmetry sponta-neously, with the occurrence of color and flavor den-sity waves . In many ways, this situation resemblesthe one encountered with dense Skyrmions (strongcoupling), suggesting the possibility of a smoothtransition . In the process, color and flavor, respec-tively, may get misaligned [10], resulting into color-flavor-locked charge density waves in a normal (largegaps) phase. The Skyrmion crystal at Iow densitymay smoothly transmute to a qualiton [10] crystalat intermediate densities, with crystalline structurecommensurate with the number of patches on theFermi surface . We note that the crystalline structurein 3 + 1 dimensions may only show up as rapid vari-ations in the response functions at momentumThis is not the case in 1+1 and 2+1 dimensions [3].
References:
D. Bailin and A . Love, Phys . Rep. 107, 325(1984).
[2] M. Alford, K . Rajagopal and F . Wilczek,Phys. Lett . B422, 247 (1998) ; R. Rapp,T . Schäfer, E .V. Shuryak and M . Velkovs-ky, Phys. Rev . Lett . 81, 53 (1998); seeF . Wilczek, hep-ph/9908480 and T. Schäfer,nucl-th/9911017 for recent reviews.
A .W . Overhauser, Adv . in Phys . 27, 343 (1978).
D .V . Deryagin, D .Y. Grigorev and V .A . Ruba-kov, Irrt .
Mod . Phys. A7, 659-681 (1992).
E. Shuster and D .T . San, hep-ph/9905448.
B .Y.-Park, M . Rho, A . Wirzba and I . Zahed,hep-ph/9910347.
T. Schäfer and F . Wilczek, hep-ph/9906512.
D .T. Son, Phys. Rev . D59, 094019 (1999),hep-phZ9812287.
D .I . Diakonov and V .Y. Petrov, Nucl . Phys.B245, 259 (1984).
[10] D .B . Kaplan, Phys . Lett . B235, 163 (1990);Nucl . Phys . B351, 137 (1991).
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[5]
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[7]
[8]
[9 ]
103
Generalized Pions in Dense QCD
M. Rho (Saclay), A . Wirzba and 1 . Zahed (Stony Brook)
The high-density region is relevant to the physicsof the early universe, compact stars and relativisticheavy ion collisions . lt is therefore essential to studyquantum chromodynamics (QCD) at large quarkdensities.
For large chemical potential, » A,2cD , quarksat the edge of the Fermi surface interact weakly,although the high degeneracy of the Fermi surfacecauses perturbation theory to fail . Thus particles canpair as diquarks and condense at the boundary of theFermi surface leading to energy gaps and thereforeto a superconducting ground state [1, 2].The resulting QCD superconductor breaks colorand flavor symmetry spontaneously. Therefore, theground state exhibits Goldstone modes that areeither particle-hole excitations (ordinary pions) orparticle-particle and hole-hole excitations (BCS pi-ons) with a mass that vanishes in the chiral limit.Effective-Lagrangian approaches to QCD in thecolor-flavor-locked (CFL) phase [3] have been dis-cussed recently [4, 5] . In general, the effective La-grangian approach provides a convenient descrip-tion of the long-wavelength physics structured byglobal flavor-color symmetries, including flavor-coloranomalies . However, it is intrinsically based an apoint-like description and does not allow a direct cal-culation of the underlying parameters . These param-eters are important for a quantitative description ofthe bulk (thermodynamic and transport) propertiesof the QCD superconductor, including for instancethe mass of the recently discussed superqualiton [4].They can only be determined using a more micro-scopic description of the QCD superconductor.
This task was done in [6] . In this letter, we havederived explicit expressions for the form factor, tem-poral and spatial decay constants of the Goldstonemodes in the weak coupling regime in the CFL phaseand to leading logarithm approximation . The self-generated form factors provide a natural cutoff toregulate the effective calentations at the Fermi sur-face . With the help of a new axial-Ward-identity inthe QCD superconductor, we could establish a a sim-ple mass formula for the Goldstone modes in weakcoupling.
In detail, in the CFL phase, the order parameter ismultidegenerate leading to Goldstone modes, withtemporal and spatial decay constants that can be cal-culated exactly in weak coupling . We find that Fg2, =p2/ir 2 and F2/F, = 1/3, where is the chemical po-tential . Thus FT is large, i .e . F72,/Gg » 1 . The corre-sponding scale is the gap constant Go 'r A * e-3- 2 / gwith the UV cutoff A* = (256p 6 /irml) p/g 5and the screening mass M E = g fl,,fl3/2ir 2 [7] . Theform factor of the generalized pinn reads G(p) =Ga sin (g In(A./p)iv/ 18)In summary, the Goldstone modes have a very small
size (of the order of the inverse momentum ex-changed between pairs at the Fermi surface irre-spectively of any screening) and propagate with aspeed that is less than the speed of light . The lat-ter property mirrors the propagation of ordinary pi-ons in nuclear matter, see [8] . The multidegeneracyof the Goldstone manifold is lifted by finite quarkmasses . The Goldstone modes are found to obey ageneralized axial Ward identity, with a very simplemass formula. We note that the small size of thepions imply that the recently discussed superquali-tons [4] are in general heavy, with a soliton massMs /Go (Fs/Go) 2 » 1 in units of the gap con-stant . The mismatch between the temporal and spa-tial decay constants may be relevant for soft pinnemission in cold and dense matter.
References:
[ 1 ] D . Bailin and A . Love, Phys . Rep. 107, 325(1984).
[2] M . Alford, K . Rajagopal and F . Wilczek,Phys . Lett . B422, 247 (1998) ; R. Rapp,T. Schäfer, E .V . Shuryak and M . Velkovs-ky, Phys. Rev. Lett . 81, 53 (1998) ; seeF. Wilczek, hep-ph/9908480 and T . Schäfer,rmel-th/9911017 for recent reviews.
C3 ] M . Alford, K . Rajagopal and F. Wilczek, Nucl.Phys. B537, 443 (1999) ; T . Schäfer and F.Wilczek, Phys . Rev . Lett . 82, 3956 (1999).
[4] D.K. Hong, M . Rho, 1 . Zahed, hep-ph/9906651,Phys . Lett . B in print.
[ 5 ] R. Casalbuoni and R . Gatto, Phys . Lett . B464,111 (1999).
[6] M . Rho, A. Wirzba, I . Zahed, hep-ph/9910550,Phys . Lett . B in print.
D.T . Son, Phys. Rev . D59, 094019 (1999);R.D . Pisarski, D .H . Rischke, nucl-th/9907041;T . Schäfer and F . Wilczek, hep-ph/9906512;B.Y. Park, M . Rho, A. Wirzba and 1 . Zahed,hep-phZ9910347.
M . Kirchbach and D .O . Riska, Nucl . Phys.A578, 511 (1994) ; V. Thorsson and A. Wirzba,Nucl . Phys. A589, 633 (1995) ; R.D. Pisarskiand M . Tytgat, Phys . Rev . D54, 2989 (1996).
C 7 ]
{ 8 ]
104
Generalized Mesons in Dense QCD
M . Rho (Saclay), E . Shuryak (Stony Brook), A . Wirzba and I . Zahed (Stony Brook)
At high quark chemical potential, quantum chromo-dynamics (QCD) is accessible to weak coupling anal-ysis, where the ground state exhibits a robust super-conducting phase, with novel and nonperturbativephenomena [1] . QCD superconductors in the color-flavor-locked (CFL) phase support excitations (gen-eralized mesons) that can be described as pairs ofparticles or holes (rather than particle-hole) arounda gapped Fermi surface.In this paper [2], we have pursued the micro-scopic analysis for the generalized scalar, vector andaxialvector mesons viewed as composites of pairsof quasiparticles or quasiholes in the CFL phase.Throughout we have only discussed the octet ofgeneralized mesons . The axial SU(3) singlet is stillexpected to be split by the color-flavor triangle-anomaly present in the CFL Phase . This issue willbe addressed elsewhere.We have shown that in the CFL phase the scalarexcitations are massless as it is the case for the pseu-doscalar excitations already discussed in [3] . The lat-ter are true Goldstone modes, while the former arewould-be Goldstone modes that combine with thelongitudinal gluons leading to the Meissner effect inthe CFL phase . In other words, the scalar modes areHiggsed by the gluons.Furthermore, we have shown that bound vector andaxial-vector excitations of particles or holes exist inthe CFL phase, and have derived an explicit relationfor their form factors and masses . To leading loga-rithm accuracy the octet of vectors are degeneratewith the octet of axial-vectors, irrespective of theirpolarization . Chiral symmetry is explicitly realizedin the vector spectrum in the CFL phase in lead-ing logarithm approximation, in spite of its breakingin general . The mass of the composite vector exci-tations is close to and bounded by twice the gap inweak coupling 2G0 , but goes asymptotically to zerowith increasing coupling thereby realizing Georgi'svector limit [4] in cold and dense matter . In the CFLsuperconductor the vector mesons are characterizedby form factors that are similar but not identical tothose of the generalized pions.Furthermore, we have shown that the composite vec-tor mesons decouple from the Noether currents andthat they do not decay to pions in leading logarithmaccuracy, contrary to their analogues in the QCDvacuum. Moreover, they decouple from the gluons inthe CFL phase as well.We have explicitly shown that the composite vectormesons can be viewed as a gauge manifestation ofa hidden local SU(3) c+v when their size is ignored(their form factor set to one) . In this limit, the effec-tive Lagrangian description suggested in [5, 6, 7] isvalid with the vector mesons described as Higgsedgauge bosons . Only in this limit, which is clearlyapproximative, do we recover concepts such as vec-
tor dominante and universality [8] . (This is of coursewhat one would expect in the normal phase as well .)In summary, a hidden local symmetry can only berevealed for zero size pairs, which is not the case formagnetically bound pairs . In other words, the zero-size limit is not compatible with the weak couplinglimit, because of the Jong-range pairing mechanismat work at large quark chemical potential.The existente of bound light scalar, vector and axial-vector mesons in QCD at high density, may haveinteresting consequences an dilepton and neutrinoemissivities in dense environments such as the onesencountered in neutron stars . For example, in youngand hot neutron stars neutrino production via quarksin the superconducting phase can be substantiallymodified if the vector excitations are deeply boundwith a non-vanishing coupling, a plausible situationin QCD in strong coupling, or by P-wave couplingto the massless scalar excitations . These excitationsmay be directly seen by scattering electrons off com-pressed nuclei (with densities that allow for a super-conducting phase to form) and may cause substan-tial soft dilepton emission in the same energy rangein "cold" heavy-ion collisions,
References:
[ 1 ] D . Bailin and A. Loire, Phys . Rep. 107,325 (1984) ; M . Alford, K . Rajagopal andF . Wilczek, Phys . Lett . B422, 247 (1998);R . Rapp, T . Schäfer, E .V. Shuryak and M . Vel-kovsky, Phys . Rev . Lett . 81, 53 (1998) ; M.Alford, K . Rajagopal and F . Wilczek, Nucl.Phys. B537, 443 (1999) ; T. Schäfer and F.Wilczek, Phys . Rev. Lett . 82, 3956 (1999) ; seeF. Wilczek, hep-ph/9908480 and T. Schäfer,nucl-th/9911017 for recent reviews.
[2] M. Rho, E . Shuryak, A . Wirzba and I . Zahed,FZJ-IKP(TH)-1999-31.
[3] M . Rho, A. Wirzba, I . Zahed, hep-ph/9910550,Phys. Lett . B in print.
[4] H. Georgi, Phys . Rev . Lett . 63, 1917 (1989);Nucl . Phys. B331, 311 (1990).
[5] D .K . Hong, M . Rh() ; 1 . Zahed, hep-ph/9906561,Phys. Lett . B in print.
[6] R. Casalbuoni and R . Gatto, Phys . Lett . B464,111 (1999).
D.T. Son, M .A . Stephanov, hep-ph/9910491.
M . Bando, T . Kugo, S. LTehara, K . Yamawakiand T. Yanagida, Phys . Rev . Lett . 54, 1215(1985).
[7]
[8 ]
105
Coupled ehannel chiral unitary meson-meson S-wave 1=1/2 scattering in the presence ofresonances
M . Jamin', J . A. Oller and A . Pich"'Institut für Theoretische Physik, Universität Heidelberg, Germany
Departamento de Ffsica Tedrica and IFIC, Valencia, Spain
In this work [1] we study the meson-meson S-wave1=1/2 scattering making use of Chiral PerturbationTheory (xPT) [2, 3] up to 0(p4 ), the inclusion ofexplicit resonance fields [4, 5] and the extension toU(3) x U(3) chiral symmetry . All these ingredientsare combined making use of the N/D method [6, 7]giving rise to fully unitarized amplitudes with Kar
and Kn' coupled channels . On the other hand, forlow energies, the approach reproduces the xPT ex-pansion plus higher order corrections.
This approach is a novel one since it is able to in-corporate the xPT amplitudes and the inclusion ofresonances and of the r)' meson in a chiral symmetricway. On the other hand, the approach has very fewfreedom since the couplings c m ) of the first res-onance (the K0*(1450)) are already fixed making useof large arguments, imposing that the scalar formfactor of Kar, Kn and Kn' vanish at infinity . On theother hand, its mass is also fixed by requiring thesaturation of the 0(p4 ) xPT counterterms, L.
These aspects are not share by the usual K-matrixapproaches which only impose unitarity but do nottake into account the chiral constraints, neither try-ing to reproduce xPT for low energies nor when in-cluding higher mass states, like the 17` meson or res-onances.
As a result our approach is very restrictive and henceis suited to discriminate between the present experi-mental ambiguities which still remain in the 1=1/2 S-wave meson-meson scattering [8, 9] . In particular, wehave seen that one is able to understand the 1=1/2and 3/2 scattering with values for the coupling con-stants c d and c, that saturate the L i coefficients.
In this sense the results of this work together withthe ones of rd . [7] agree with the conclusions in ref.[4] about the resonance saturation of the xPT O(p4 )counterterms. However, in that work the authorsconsider the first scalar nonet with a mass around1 Gev and including the ao(980) resonance . How-
ever, from refs . [1, 7] we can say that this is notthe case . The picture is that there is a lighter nonetscalar which embodies the oh k, ao(980) and a strongcontribution to the f0 (980) resonance which is of dy-namical origin and hence subleading in large N c . Thescalar nonet, leading in this counting and responsi-ble for the saturation of the L i couplings, is anotherone. We have determined its mass to be around L2GeV . This nonet embodies an octet formed by the1).i "(1430), a 0 (1450) and a fo with a mass higherthan 1 .2 GeV and a singlet which contributes to the
f0 (980) resonance.Finally, we stress that the situation for the experi-mental data in these channels has still to be improved
106
both in the 1=1/2 and 3/2 channels, and that an esti-mation of the associated systematic errors should bewelcome. For the 1=1/2 channel we only agree withthe solution C of [9] for energies higher than 1 .5 GeVand disagree with the data of ref . [8] for those ener-gies . With respect the 1=3/2 case, we disagree withref . [9] for low energies but we agree with order data[10].On the other, in the near future, we will use thecalculated S-wave meson-meson 1=1/2 amplitudesin order to calculate the scalar 1=1/2 form factor . Inthis way, we will be able to study its influence in themass of the strange quark [11].
References:
M . Jamin, J . A . Oller and A . Pich, 'Coupledchannel chiral unitary S-wave 1=1/2 scatteringin the presence of resonances', in progress.
J . Gasser and H . Leutwyler, Ann . Phys. NY 158(1984) 142 ; J . Gasser and H. Leutwyler, Nucl.Phys . B250 (1985) 465, 517, 539.
V . Bernard, N . Kaiser and U . G . Meißner, Nucl.Phys . B357 (1991) 129.
[4] G. Ecker, J . Gasser, A . Pich and E . de Rafael,Nucl . Phys . B321 (1989) 311.
V. Bernard, N . Kaiser and U . G . Meißner, Nucl.Phys . B364 (1991) 283.
G . Chew and S . Mandelstam, Phys . Rev. 119
(1960) 467.
J . A. Oller and E. Oset, Phys . Rev . 160 (1999)074023.
D . Aston et ah, Nucl . Phys. B296 (1988) 493.
P. Estabrooks et ah, Nucl . Phys . B133 (1978)490
[10] Y. Cho et ah, Phys . Lett . B32 (1970) 409 ; A.M . Bakker et ah, Nucl . Phys. B24 (1970) 211.
[11] M. Jamin, Nucl . Phys. Proc . Suppl . 64 (1998)250.
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[9]
Chiral Unitary approach to meson-meson and meson-baryon interactions and nuclearapplieations
J . A . Oller, E . Oseta , A . Ramosb
Departamento de Ffsica Te6rica and IFIC, Valencia, SpainDepartament d'Estructura i Constituents de la Materia, Universitat de Barcelona, Spain
This work [1] is a report about the vast ammount ofresults that have been derived following the so calledChiral Unitary Approach, which in fad, refers to aset of approaches with increasing order of generality.After a short review of the basic concepts of chi-ral symmetry and of several chiral Lagrangians wehave discussed various nonperturbative methods todeal with the meson-meson and meson-baryon in-teractions which allow one to extend the region ofapplicability of the theory to higher energies thanin xPT, where the Iow lying mesonic and baryonicresonances appear . The common ground of all thesemethods was the exact implementation of unitarityin coupled channels . The constraints imposed by uni-tarity allow one to extract information contained inthe chiral Lagrangians which is not accessible withthe standard xPT expansion.One of the procedures followed was the Inverse Am-plitude Method [3], which relies upon the expansionof the inverse of the scattering matrix and gives riseto an expansion in powers of p 2 with a larger conver-gence radius than xPT. In that method one couldextend the predictions for meson-meson interactionsup to about 1 .2 GeV, and all mesonic resonances upto this energy where well reproduced, as well as phaseshifts and inelasticities.A second method [4]relied upon the use of the N/Dmethod and the hypothesis of resonance saturation.In this case, the use of the information containedin the lowest order chiral Lagrangian, together withchiral loops and the explicit exchange of some reso-nances, which are genuine QCD states in the sensethat they would remain in the large limit, allowalso a good description of the meson-meson data upto about 1 .5 GeV . This second method is particularlyrewarding for it allows one to dig into the nature ofthe mesonic resonances and separate those which arepreexisting QCD resonances, in the Limit of large Nc,from others which qualify as dynamical meson-mesonresonances coming from the multiple scattering ofthe mesons. In this way, it was stablished that theIow Iying scalar resonances, the er, ic, a 0 (980) and tolarge extent the fo(980), are generated dynamicallyfrom multiple scattering from the lowest order chiralLagrangian . On the contrary, a singlet contributionto the fo(980) and a scalar octet around 1 .35 GeVwould be the fightest preexisting scalar states . Thislatter method also allows one to understand why inthe case of the scalar sector a succesful reproduc-tion of the data can be obtained simply by meansof the lowest order chiral Lagrangian and the Bethe-Salpeter equation, together with a suitable cut off,or regularizing scale.In the meson-baryon sector applieations were only
done in the scalar sector taking advantage of the sim-plification of the Bethe-Salpeter equation, which wasfound to be a suitable approach mach as in the case ofthe meson-meson scalar sector . In this case, Iow lyingresonances like the A(1405) [5] or the N(1535) weregenerated within that approach, and a good repro-duction of the Iow energy scattering data was found,particularly in the case of the K - N interaction andcoupled channels.Applications to problems of initial and final state in-teraction have also been shown . Since the energy re-gion of applicability of the reported methods is muchlarger than the one of xPT, one could tackle manynew problems formerly inaccessible with plain xPTtheory.We have also shown how these chiral approachesto the meson-baryon and meson-meson interactionshave repercussions in nuclear physics and providea new perspective into problems which have beenrather controversial up to now, like the 7t7r scatter-ing in a nuclear medium or the nucleus interac-tion . Several reactions which can bring new Iight intothese problems have also been reviewed and the im-plementation of the experiments is already plannedin some laboratories.The methods exposed here open new possibilities toface a large number of problems, of which we haveonly given a few examples . Extension of the methodsto higher energies, the incorporation of channels withmore than two particles, and application to otherphysical domains remain as challenges for the future.
References:
[1] J . A . Oller, E . Oset and A . Ramos, 'ChiralUnitary approach to meson-meson and meson-baryon interactions and nuclear applieations',FZJ-IKP(TH)-1999-36, to be published in Prog.Part . Nucl . Phys . Vol . 45, issue 1.
[2] J . Gasser and H . Leutwyler, Ann . Phys . NY 158
(1984) 142 ; J . Gasser and H. Leutwyler, Nucl.Phys . B250 (1985) 465, 517, 539.
[3 ] T. N. Truong, Phys . Rev. Lett . 61 (1988) 2526;Phys . Rev. Lett . 67 (1991) 2260 ; A . Dobado, M.J . Herrera and T. N . Truong, Phys . Lett . B235(1990) 134 ; A . Dobado and J . R . Peläez, Phys.Rev. D47 (1993) 4883 ; Phys . Rev . D56 (1997)3057; J . A. Oller, E . Oset and J . R. Peläez,Phys . Rev. Lett . 80 (1998) 3452.
[4] J . A . Oller and E . Oset, Phys . Rev . D60 (1999)074023.
[5 ] E . Oset and A . Ramos, Nuel . Phys . A635
(1998) 99.
107
Neutral pion polarizabilities and final state interactions of the 7t 0 7t0 System
G.C. Gellas, T .R. Hemmert and N .N. Nikolaev
1. Overlook
A composite system is characterized besides its fun-damental parameters - such as the electric Charge,the magnetic moment and the mass - by its electricand magnetic polarizabilities describing the responseof it within external electric/magnetic field and ap-pearing in the Compton amplitude in the Iow energylimit . The polarizabilities of neutral pions are themain issue under study in our work [1] . As far as nu-merical results from the experimental point of vieware concerned, one of the methods that can be used isthe so called "nucleus Coulomb interaction " . Thereare two possible ways to realize this method in anexperiment: the radiative scattering zrA -4 tr7A of apion on a nucleus and the photoproduction of pionpairs in the Coulomb field of a nucleus 7A -4 rrtrA.The experiments under discussion are based on thefast that for sufficiently small momentum transfersthe interaction of high energy particles with nucleiis extremely peripheral and thus dominated by scat-tering on the virtual photons of the Coulomb field ofthe nucleus . The photoproduction of a neutral pionpair provides a source of information on the process-y-y -4 )r 0 7r 0 , via extrapolation . . Quite recent experi-mental data are provided by the Crystal Ball Collab-oration [2] and in addition the saure process is underactive discussion in the context of the physical pro-gramme at DA' NE [3].
2 The caleulatian
The expression of the amplitude of the reaction7(q 1 )A -4 7r«pl)7r«p2)A is the following [4],
Tc .= 2M A ', z'F (4'2 1 2 ( 1 )
where MA and ZA are, respectively, the mass and thecharge of the nucleus, -y"'2 is the momentum trans-fered by the virtual photon, FA (i2) is the nuclearform factor which includes nuclear absorption and
T(o'*-'0z0) is the tensor component of the ampli-
tude of the process -y(q l )7* (q2) -+ 7r«pl)7r«p2) . Thedifferential cross section is defined as
c
32(2tr) 5eMiE1 E2
x(5(E I + E2 - c) 2ITc{2d3pid3p2d3g2,
(2)
where Ei and 15i (i=1, 2) and e are the energies andmomenta of the pions and the energy of the incidentreal photon, respectively . For large energies of theincident real photon and for small momentum trans-fers to the recoil nucleus, neglecting the off-shellnessof the Coulomb photon and nuclear corrections, themethod of equivelant photons allows us to relate the
108
differential cross section for photoproduction of pionpairs on nuclei to the total cross section for the pro-cess -yry -4- tr D lr0 . Our calculation is an extension andimprovement of these approximations via includingoff-shell corrections for the Coulomb virtual photonin the elementary reaction 7-y* fro r° and by tak-ing into account in the form factor of the nucleus thenuclear structure and absorption.
The leading -yry* 7t 0 7r 0 amplitude is the one frommeson loops at 0(p4 ) in ChPT without countert-erms and one of the main issues that we have totake care about is the large corrections to it requiredby unitarity. In the threshold region the phase ofits components fr(s), where 1 = 0,2 refers to theisospin of the final rr state, is required by unitarityto be equal to the corresponding rr phase shift 51 (s).When s 16m2.n., with the pion mass, inelasticreactions involving four pions are allowed . However,the inelasticity is small, being of order q 8 in the chi-ral expansion and also suppressed by phase spaceconsiderations . The functions fr(s) are then analyticfunctions of s except for cuts along the positive andnegative real axis and the single-channel final stateunitarization Problem has a simple solution in termsof the Omnes expression [5]:
( f~ds' S1(s»
D (s) = exp
( 3 ))r
si s' - S
2 '
The result must have the form
fr(s) = (s)DZ«s), (4)
where g l (s) is an analytic function with no cuts alongthe positive real axis . The underlying physical pic-ture [6] is the strong attractive rr scattering in thefinal isospin-zero S-state . The next steil is to com-pare the outcome of our unitarized amplitude withthe experimental dato., and proceed with the extrac-tion of the polarizabilities.
Referenees:
G .C . Genas, T .R. Hemmert and N .N. Nikolaev,in preparation.
[2] Crystal Ball Callaboration, H . Marsiske et ah,Phys . Rev . D 41, 3324 (1990).
[3] M .R. Pennington, in "The Second DAefilEPhysics Handbock" Vol II, 379 (1995), ed . byL . Maiani, G . Pancheri, N . Paver.
[4] e .g . A .A. Bel'kov, M . Düng and A .V . Lanyov, J.Phys . G 23, 823 (1997).
R . Omnes, Nuovo Cimento 8, 316 (1958).
J. Gasser and Ulf-G . Meißner, Nucl . Phys . B357, 90 (1991).
doi.( syA-rirA)
8(3) (15i + il 42)
[5]
[6]
Spin polarizabilities of the nucleon
G .C . Gellas, T .R. Hemmert, C .N. Ktorides a and Ulf-G . MeißnerDept. of Physics, Univ . of Athens, Greece
1. Introduetion
Low energy Compton scattering off the nucleon isone of the most important probes to unravel thenonperturbative structure of QCD . In the Jong wave-length limit only the charge of the target can be de-teeted and the cross section is given by the Powellformula [1] . At higher energies, the internal structureof the system, in terms of three quarks surroundedby a pion cloud, slowly becomes visible . The exter-nal electromagnetic field induces dipole moments, Bi-
ther electric or magnetic, and modifies the effectiveHamiltonianleading to the Powell result . To third or-der in the frequency of the incoming photon, the am-plitude is described in terms of six parameters thatcan not be fixed by the low-energy theorems . Theseare the electric and magnetic polarizabilities of thenucleon, cr i , ßu, respectively, appearing already atorder
and the so-called spin polarizabilities -y i ,1,2,3,4, appearing to order w 3 [2] . We focus on
the last four given the fact that they provide a probefor the nucleon structure depending on its spin . Atpresent there are no sufficient dato on these . Dou-ble polarization experiments are currently runningand the situation will be improved quite soon. Ourcalculation was performed, up to now, in the con-text of Heavy Baryon Chiral Perturbation Theory(HBChPT) to order p4 , extending previous work [3],[4] . This is the ferst order in which the isovector com-ponents start contributing and so our results are dif-ferent for the proton and the neutron.
2. The Calculation
Assuming invariance under parity, charge conjuga-tion time reversal symmetry, the general ampli-tude for Compton scattering can be written in termsof six structure dependent functions A i (w, 6),1, . . .,6, with w denoting the photon energy in thec .m. frame and 6 being the c .m. scattering angle:
T
A 1 (w, 61 )i'[' - 7+ A 2 (w, 9)
.
+ iA 3(w, x
+ iA 4 (w, ,9)o- x h)r'+ iA 5 (w , 0)i5'- [(r' x k) k '
(e- x ic»e-'
+ iA 6 (w,9)h"i - Ur' x he' - k'
(i° x k.)i"' k] .
( 1 )
Here k(e"[ , are the polarization vector and direc-tion of the incident (final) photon while representsthe (spin) polarization vector of the nucleon.The A i functions admit a contribution from theWess-Zumino-Witten Lagrangian called "anoma-lous" or the "pion-pole" one . The remaining part is
expanded in powers of w . For the A 5 , for example,we have,
e 2 w /
+
0 )A 5( w , ) fc'.g. .
nr24,
0
e 2 w 2 ( a 0
4M 3 0 b
4(P)
00
'Y4(n)
where a = 1 + Kp -'r + (1 + Kp ) 2 cos0, b --K,2 (1 -cos9), the subscript p, n refers to the proton, neu-tron, respectively and K p,r, denotes the correspond-ing anomalous magnetic moment.To order p 4 only one loop diagrams with one inser-tion the 0(p2 ) Lagrangian contribute and wefound that the spin dependent part of the amplitudeis free of any counterterm contribution besides theanomalous magnetic moments . Our p/MN correctionto the 0(p3 ) result given in [3, 4], is [5],
1
e 2 gA')'4(p) = -
9 2
( 11 + 8 ( 1 +Kp)) ( 3 )8 192F,iir m 7 :M N
74(n) - 9219ir 2m,MN
Extension of the present work to the polarizabilitiesentering in order 0(w 4 ) [6] is straightforward . Fur-thermore, explicit introduction of the A(1232) de-grees of freedom in the context of the Small Scale Ex-pansion (SSE) scheme is under way . We mention thatsuch a calculation will give the effects of the d(1232)on the yi with 1-loop technology, whereas one has togo to 0(p5 ), for the saure reason, in HBChPT whichmeans that two loop effects will be involved.
References:
[1] J .L . Powell, Phys . Rev. 75, 32 (1949).
[2] S . Ragusa, Phys . Rev . D 47, 3757 (1993) ; Phys.Rev . D 49, 3157 (1994).
[3] V. Bernard, N . Kaiser, Ulf-G . Meißner, Int.Mod. Phys . E 4, 95 (1993).
[4] T.R . Hemmert, B .R. Holstein, J . Kambor andG . Knöchlein, Phys . Rev . D 57, 5746 (1998).
[5] G .C. Genas, T .R. Hemmert, C .N. Ktorides andUlf-G . Meißner, in preparation.
[6] B .R. Holstein, D . Drechsel, B . Pasquini, M . Van-derhaeghen, preprint no . hep-ph/9910427 .
(2)
e2gA
(11 - 8irn) .
(4)
109
Low energy Compton scattering with explicit 3.(123 degrees of freedom
G .C. Genas, T .R. Hemmert, C .N . Ktoridesa and Ulf-G . MeißnerDept . of Physics, Univ . of Athens, Greece
1. Overlook
The aim of the present work is to illustrate the partic-ular role of the A(1232) dynamics in the Iow energyCompton scattering off the nucleon . Up to 50MeVphoton energies the experimental dato can be de-seribed quite well with the Powell model in the con-text of which the nucleon is considered as a pointparticle with spin 1/2 and anomalous magnetic mo-ment /4 . If one increases the energy of the incom-ing photon beam one starts seeing deviations fromthe simple Powell predictions, as one is picking upsensitivity to the internal structure of the nucleon.The latter is parametrized in terms of 6 polarizabil-ities aE, /3M, 71, 72, 73 and -y4 which cannot be de-termined by symmetry considerations . In unpolar-ized Compton scattering the electric polarizability
aE and the magnetic polarizability describe theleading structure dependent effects and account forthe deviation of the cross section from the Powell re-sult . From the experimental point of view one of themost recent fits yield
a (Z ) = (12.1±0 .8±0 .5) x 10-4( 1 )
t-rt_ (2 .1
0 .8
0 .5) x 10-4 f
,
(2)
indicating that the nucleon is a rather "stiff" objectthat cannot easily be deformed in the electric andmagnetic Held of the incoming and outgoing photon.In 1992 it was found in an 0(p3) HBChPT calcu-lation that ChPT can very nicely explain the mag-nitude of both aE and ß as being dominated by7rN loop effects . According to this interpretation theonly structure of the nucleon a Iow energy photonresolves when undergoing Compton scattering wouldtherefore be given by the nucleon's "pion-cloud " , inmarked contrast to analyses using dispersion rela-
tions . A subsequent 0(p4) calculation [1] proved thatthere are indeed only small corrections to the 0(p3 )result, and the sum of the two orders gives
O(p4)= (10 .5 ± 2 .0) x 10-4( 3 )
o(p 4 )is-i. (3 .5 ± 3 .6) x 10-4 f 3 .
(4)
We note the agreement with current experimentalresults, but also that there exists a considerable the-oretical uncertainty . The main reason for this uncer-tainty is the first nucleon resonance A(I232), whichin HBChPT can only be included via counterterms,
i .e . is taken to be infinitely heavy compared to thenucleon . Recently a systematic formalism, called the"small scale expansion (SSE)" , has been developed toinclude the A(1232) as an explicit degree of freedom
110
in ChPT [2] . The six polarizabilities of the nucleonhave being calculated to 0(63) within this approachand the outcome for the spin-independent ones is [3]
[12 .2(Nir - loop) + 0(A - pole)
+ 4.2(Air - loop)] x 10 -4f
[1 .2(Nrr - loop) + 7 .2(A - pole)
+ 0 .7(Air - loop)] x 10 -4fm 3 . (6)
A quick glance at these results shows that the 0(6 3 )
calculation is not able to reproduce the experimentalvalues . An 0(e 4 ) project in the forward direction [4]is in progress . All the loop effects involved have beingealeulated. Among them the large diamagnetic "re-coil" contribution of the rrN loops in the case of ,em
is included . In analogy to the 0(p4 ) case we expectthat this contribution will cancel the large paramag-netism of the Aspole in the same polarizability . Alsothe same calculation will shed more light on the un-derlying physics in aE . According to Eq .(5) thereis a large contribution from the rrZlis continuum . InHBChPT it is very common to subsume pole con-tributions from nucleon resonances in counterterms,but there is no agreement in the chiral communityyet how one would include rrA loop effects in coun-terterms at a given order . Usually these effects arequite small and can be safely neglected, but the 0(63)
calculation of aE shows a strong counter example . Sothe current 0(e 4 ) effort will also shed more light onthe issue of resonance saturation of counterterms inthe baryon sector in general . What remains to bedone is the consistent determination of the low en-ergy constants that will appear . These are the 0(p4 )
constants in the two-photon seagull vertices and theIow energy constants of the 0(c 3 ) -yNA. Lagrangian.For the latter we can use the values being determinedin [5] whereas for the former we will fit to the existentexperimental dato . We are working currently on thisand we expect to report on our results quite soon.
References:
V . Bernard et al ., Z. Phys . A 348, 317 (1994).
T .R. Hemmert et al ., J . Phys . G 24, 1831(1998).
T.R. Hemmert et ah, Phys. Rev . D 57, 5746(1998).
[4] G .C . Gellas, T .R. Hemmert, C .N . Ktorides andUlf-G . Meißner, in preparation.
[5] G.C. Genas et ah, Phys. Rev . D 60 054022(1999).
a E
3 (Z)
a(E P)
o(r3)
[2]
[3]
Generalized Polarizabilities of the Nucleon
T.R. Hemmert, B .R. Holstein (UMASS), G . Knöchlein (LRP) and D . Drechsel (IKP-Mainz
Using the techniques of effective chiral field theorieswe evaluated [1] the so called "generalized polariz-abilities" (GPs) [2], which characterize the structuredependent component of virtual Compton scatter-ing (VCS) off the nucleon as probed in the electronscattering reaction eN -+ e`N-y . Results are given forboth spin-dependent and sein-independent structureeffects to 0(p3) in SU(2) Heavy Baryon Chiral Per-turbation Theory and to 0(e 3) in the SU(2) "SmallScale Expansion".In the figure below we show the 0(p3 ) HBChPTresults for the variation of the generalized elec-tric [magnetic] polarizabilities ä E (i2 ), [3m(ii 2 )],where 2 correpsonds to the 3-momentum transfer(squared) in units of [GeV 2] from the electrons tothe nucleon. Results for other GPs, in particular forthe spin-dependent GPs can be found in [1].
ä(3)( ;i2) [10-4
2
0 .1
0 .2
0 .3
0 .4
0 .5
1 .0
0 .5
0 .1
0 .2
0 .3
0 .4
0 .5
Quantity
Expt .
Chpt LSM ELM NR
PLL - E PTT 30 .5 ± 6 .2
26 .3
10 .9
5 .9
17 .0PLT
-8 .6 ± 3 .9
-5 .7
0
-1 .9
-1 .7
Table 1 : Experimental values of the response func-tions in units of [GeV 2] measured at MAMI atfour-momentum transfer (squared) Q 2 = 0.33 GeV 2compared with predictions from chiral perturbationtheory at 0(p3 ) [4], the linear sigma model (LSM) ofMetz and Drechsel [5], the effective lagrangian model(ELM) of Vanderhaeghen [6], and the nonrelativisticquark model (NR) of Guichon et al . [2] . This tableis based on ref.[3].
The comparison between theory and experimentoccurs on the level of the response functionsPLL, PTT, PLT, which are dominated by Bethe-Heitler scattering modified by small effects due tothe GPs. Results of the first VCS measurement onthe proton have recently been published [3] and areshown in the table above.
References:
T.R. Hemmert, B.R . Holstein, G . Knöchlein andD. Drechsel, [nucl-th/9910036] ; submitted toPhys . Rev . D.
[2] P .A .M. Guichon, G .Q. LM, and A .W. Thomas,Nucl . Phys. A591, 606 (1995) and Aust . J.Phys . 49, 905 (1996).
[3] Roche et al ., "The first dedicated VirtualCompton Scattering experiment at MAMI", tobe published;N . d'Hose, Proceedings of Baryons 98, p .380ff;World Scientific (Singapore) 1999.
[4] T .R. Hemmert, B .R. Holstein, G . Knöchlein andS . Scherer, Phys . Rev. Lett . 79, 22 (1997).
[5] A . Metz and D . Drechsel, Z . Phys. A356, 351(1996) and A359, 165 (1997).
[6] M. Vanderhaeghen, Phys . Lett . B368, 13(1996).
.i 2
1;2
Radiative Pion Capture on a Nucleon
H.W. Fearing (TRIUMF), T .R. Hemmert and R . Lewis (U . Regina
The differential cross sections for rr- p -4 -yn andlr+ n 4-> yp have been computed [1] up to 0(p3) inheavy baryon chiral perturbation theory (HBChPT).The expressions at 0(p) and 0(p2 ) have no free pa-rameters . There are three unknown parameters at0(p3 ) which are determined by fitting to recent ex-perimental data from TRIUMF [2] . The s-wave mul-tipole Eo+ of this reaction is dominated by the Kroll-Ruderman term and has already been analyzed atthreshold in the inverse reaction of charged pionphoto-production [3] . In our work we focus on theenergy-dependence of the multipoles and, in partie-ular, are interested in a study of the correspond-ing p-wave multipoles . Although the obtained fithas an acceptable x 2 , it is noted that one of ourHBChPT parameters so far acquires a rather largevalue, thus raising concerns about the rate of con-vergence of the chiral expansion for the p-wave mul-tipoles in charged pion photo-production/radiativecapture . This is rather surprising since the corre-sponding p-wave multipoles in neutral pion photo-production [4] show an extremely fast convergencein their chiral expansion.We are currently investigating possible physics see-narios that would lead to such a large counterterm.One possibility under study is the concern that-although several counterterm structures appear at0(p3)-the coupling structure might be such thatsome important effects in the p-wave multipoles dueto explicit A(1232) degrees of freedom might be miss-ing in the HBChPT calculation, which only allowsfor explicit pion and nucleon degrees of freedom. Theother possibility under study concerns the behaviorof the imaginary parts of the p-wave multipoles . Asthe three 0(p3) counterterms are fitted to the dif-ferential cross-sections of the reaction -4 n-y
for kinetic pion energies between 10 to 40 MeV, itis feared that the imaginary parts of the multipolesat the higher pionic energies might already lie out-side the range of validity of the 0(p 3 ) calculation.We are currently investigating the rote of the imag-inary parts in this energy range via a comparisonwith the dispersion theoretical analysis of the pionphoto-production multipoles from the Mainz group
[5]-
References:
H .W. Fearing, T .R. Hemmert and R. Lewis,forthcoming.
[2] M . Salomon, D . F . Measday, J .-M . Poutissouand B . C. Robertson, Nucl . Phys. A414, 493c(1984);D . Hutcheon, private communication.
[3] V. Bernard, N . Kaiser and U.-G . Meißner, Phys.Lett . B383, 116, (1996) .
3
10-1 .0
-0 .5
0.0
0.5
1 .0=se c,.
Figure 1 : The reaction 7r- p -4 -yn, quotedas center-of-mass cross sections for the inverse-yn -4 7t-p reaction . Experimental data are com-pared to the HBChPT predictions at 0(p) (dot-ted line), 0(p 2) (dashed line), and O(p 3 ) (solidline) . (a)
= 9 .88 MeV, (c) T„r = 19 .85 MeV,(e)
= 39 .3 MeV.
[4] V . Bernard, N . Kaiser and U .-G . Meißner, Z.Phys . C70, 483 (1996).
[5] O . Hanstein, D. Drechsel and L . Tiator, Phys.Lett . B399, 13 (1997) ; Nucl . Phys. A632, 561(1998).
e
112
Nucleon-nucleon FSI effeets in meson production in NN-collisions
V. Harn', A. Gasparian', J . Haidenbauer, A . Kudryavtseva , 1 Speth
lt is a well known fact that the energy dependencefor reactions of the type NN -+ NNx near thresholdis mainly determined by the strong NN interactionin the final state [1] . Therefore several authors (see,e .g ., Ref. [2]) used the simple prescription
J ~ i = Ap0nrod
to inelude effects fron' the NN final state interac-tion (FSI) in their studies of the reaction pp ppx(x = rc0 ,It,rl', etc .) . In Eq. (1) 5 = 5(k) is theproton-proton (pp) phase shift, C a normalizationconstant, and Ap"T,od the on-shell production ampli-tude . In such an approach FSI effects are universal,
e . do not depend on the specific meson emitted.Recently, Hanhart and Nakayama [3] have criticizedthe above approach . In particular, they pointed outthat the evaluation of the total reaction amplitudeby just multiplying the production amplitude withthe on-shell NN T-matrix is not acceptable for ob-taining quantitative predictions . Their work is basedon a more general approach [3] where the reactionamplitude is determined from the DWBA expression
A p',.%d + A;,f afd GoTpp
(2)
Here Tpp is the half-off-shell pp T-matrix and Go thefree Green's function.We present results of a detailed study on the validityof the multiplication prescription for FSI effects . Forthe interaction in the final state we employ realisticNN models . The elementary production amplitudeAprod is chosen to be simple, i . e . spin-independent.Specifically we use
Aprod
t ,u2
which corresponds to the exchange of a scalar mesonwith mass '1 in the techannel . A is a constant . Thereaction amplitude based on this production ampli-tude is given by
Ap°rodT(,»f(k') .
(4)
For near-threshold meson production we get the fol-lowing simplified expression for e (;f f :
dqq Tpp(q, k)q 2 -k 2 -i0
( 5 )
m and M are the masses of the nucleon and the pro-duced meson, respectively.Let us analyze the expression (5) . For Iight mesons,M « m, we get r sis, VimM and = + M 2 /4.Consequently the integral on the r .h .s . of (5) de-pends on M . In the opposite case of heavy mesonproduction, M » m, we get r iss, rn and A 2
m 2 ,and thus fff (ef ;(k) does not depend on the mass of theemitted meson x . In Fig . 1 we give examples of thepp enhancement factor Fpp =1 94,7; (k) 1 2 calculatedfor the Bonn NN potential and assuming differentmasses for the emitted meson . The difference in theenergy dependence for the various curves is rathersmall . However, there is a strong influence of themeson mass on the absolute magnitude of the en-hancement factor . The behavior of Fpp utilizing theParis NN potential is similar to the one for the Bonnmodel.
Fig. 1 : The enhancement factor Fpp calculated for dif-ferent masses of the produced mesons.
Our study shows that effects of the (NN) FSI cannotbe factorized from the production amplitude. This isin agreement with the conclusion drawn in Ref . [3].The absolute value of the enhancement from the FSIdepends strongly on the momentum transfer, e . isnot universal . Only in the Limit of large momentumtransfer, e . for the case of production of veryheavy mesons, the factorization assumption mightbe justified.
'also at : Inst . of Theoretical and Experimental Physics,117258, B .Cheremushkinskaya 25, Moscow, Russia
Referencesi[1] K. Watson, Phys . Rev . 88, 1163 (1952) ; A . Migdal,
JETP 1, 2 (1955).E . Gedalin et al ., Nucl . Phys . A634, 368 (1998);A. Sibirtsev and W . Cassing, nucl-th/9904046 ; V.Bernard et al ., Eur . Phys . 2 . A 4, 259 (1999)
[3] C. Hanhart and K . Nakayama, Phys . Bett . B 454,176 (1999).
( 1 )sin
kC
A( 3 )
where
o 0
2
- M=135 MeV-- M=550 MeV 1-- M=958 MeV
00
113
w- and a-meson production in the reaction pn -+ dM near threshold
V . Yu . Grishina a '*, L .A. Kondratyuk i", M . Biischer*, J . Haidenbauer, and J . Speth
In a previous paper [1] we investigated near-threshold production of 17 and rl` mesons in the re-action pn dM . The calculations were done withinthe framework of the two-step model (TSM) whichis based on triangle graphs with rr, p and w mesonsin the intermediate state. In that work the elemen-tary amplitudes rrN --+ NM, pN NM andwN --+ NM were treated as "frozen" effective con-stants. This approach is expected to be valid forthose cases where the elementary amplitudes aredominated by s-channel exchanges, e .g ., by broadresonances (S11 (1535) for n- and S 11 (1980) for y'production) . However, for w and production thedominant contributions to the elementary amplitudecome presumably from the t-channel exchanges of 7r-and p mesons . Such 1-channel models were used foranalysis of the near-threshold production of vectormesons in -ylv° and irN collisions in Refs . [2, 3, 4].In this case we can no longer treat the elementaryamplitude as a constant because its momentum de-pendence is comparable to the one of the meson prop-agator in the triangle graph . Moreover we should becareful to avoid double counting as it would hap-pen if we consider, for example, ir-meson exchangein the pN
Nw amplitude and p exchange in thetrN Nw amplitude . Thus, instead of triangle di-agrams with rr and p exchanges we should consider(standard) meson exchange currents, i .e . diagramswith an 7rpW (or 7r0) vertex which couples to thetwo nucleons via the ir and p.
The cross section of the reaction pn dw which isshown in Fig . 1 is calculated with the following cou-pling constants : f,NN ts 1, G 2pNN /4n- = 0 .84 (K p =6 .1), yp,„, 11.8 . The form factors at the rNN andpNN vertices were taken to be of monopole typewith cut-off parameters A,= 0 .8 - 1 .05 GeV and A p=1 .4 GeV.
In Fig . 1 we show also experimental data on thenear-threshold production of w mesons in the reac-tion pp ppw [5] . Evidently, the predicted crosssections for w production with the deuteron in thefinal state (solid curves, calculated with A,= 0 .8(lower curve) and 1 .05 GeV (upper curve), respec-tively) are much larger than those of the reactionpp ppw . This is very similar to the case of pro-duction . Note that the cross section of the reactionpn --+ dw which corresponds to the meson-exchange-current diagrams is smaller by a factor of 2 thanthe cross sections of the same reaction calculatedwith "frozen" elementary amplitudes [6] . The 0/w ra-tio which we get is equal to (11 ± 4) x 10' whichshould be compared with the value (30 ± 7) x 10 -3received with "frozen" elementary amplitudes [6].
In conclusion, the TSM predicts cross sections for thereaction pn -+ dw near threshold which are consid-erahly larger than the cross sections for the reactionpp
ppw . The values of the cross sections of the
10
20
30
40
50
60
,MeV
Fig . 1 : Cross section of the reaction pn -> dw as afunction of the cm excess energy. The dashedcurve corresponds to the meson exchange cur-rent with the combined ~rp exchange . Thedash-dotted curve includes also w exchange.The solid curve includes all contributionsmentioned above multiplied with a normal-ization factor N = 0 .46 in order to take intoaccount effects from the initial state inter-action . The upper and lower (dashed, solidand dash-dotted) curves are the results ob-tained using A,,.= 0.8 and 1 .05 GeV, respec-tively. The points represent data on the reac-tion pp -ei- ppw [5].
reactions pn --+ dw and pn --,i, d(b are sensitive tothe dynamics of the elementary reactions and theirmeasurements can be used for understanding whichmechanism dominates in each case : s-channel nu-cleon resonance contribution or t-channel meson ex-change. The cross sections of the reactions pn -+ dwand pn ei+ d are planned to be measured at ANKE
[7] -
References:
[1] V. Yu . Grishina et al ., nuc1-th/9905049 ; sub-mitted to Phys . Lekt . B
[2] B . Friman and M . Soyeur, Nyel .Phys. A600(1996) 477;
[3] G .1 . Lykasov et al ., Pur. Phys. J. A6 (1999) 71.[4] A . Sibirtsev and W . Cassing, nucl-th/9907059;[5] F . Hibou et al ., nucl-ex/9903003.[6] V . Yu . Grishina et al ., nudl-th/9906064 ; Yad.
Fiz . (Physics of Atom . Nucl .) to be published[7] M. IUscher et
COSY proposal #75 (1998).
a Institute for Nuclear Research, 60th October An-niversary Prospect 7A, 117312 Moscow, Russiab Institute of Theoretical and Experimental Physics,B . Cheremushkinskaya 25, 117259 Moscow, Russia
Supported by DFG and RFFI.
114
Near threshold A and E° production in pp callisions
A. Gasparian', J . Haidenbauer, C . Hanhart 2 , L . Kondratyuk l , J . Speth
In a recent measurement of the reactions pp -*pAK+ and pp --+ pE'K+ near their thresholds itwas found that the cross section for E° productionis about a factor of 30 smaller than the one for Aproduction [1] . Here we want to report on an ex-ploratory investigation of the origin of this strongsuppression of the near-threshold production . Inparticular we want to examine a possible explana-tion that was suggested in Ref. [1], namely effectsfrom the strong EN final state interaction (FSI) lead-ing to a EN -+ AN conversion. We treat the asso-ciated strangeness production in the standard dis-torted wave Born approximation . We assume thatthe strangeness production process is governed bythe and K exchange mechanisms . In order to havea solid basis for our study of possible conversion ef-fects we employ a microscopic YN interaction modeldeveloped by the Jülich group (specifically model Aof Ref. [2]) . This model is derived in the meson-exchange picture and takes into account the couplingbetween the AN and EN channels.
The vertex parameters (coupling constants, form fac-tors) appearing at the isNN and KNY vertices inthe production diagrams are taken over from theJülich YN interaction . The elementary amplitudes
TK N and TrN ...+ K Y are taken from corresponding mi-croscopic models [3, 4] that were developed by ourgroup . However, for simplicity reasons we use thescattering length and on-shell threshold amplitudes,respectively, instead of the full (off-shell) KN andrrN -4> KY t-matrices . The off-shell extrapolationof the amplitudes is done by multiplying those quan-tities with the same form factor that is used at thevertex where the exchanged meson is emitted . Onlys-waves are considered.
We do not take into account the initial state interac-tion (ISI) between the protons . Therefore we expectan overestimation of the cross sections in our calcu-lation [5] . But since the thresholds for the A andproduction are relatively dose together and the en-ergy dependence of the NN interaction is relativelyweak in this energy region the ISI effects should bevery similar for the two strangeness production chan-nels and therefore should roughly drop out when Ta-tios of the cross sections are taken.
The cross section ratio for K exchange alone andbased on the Born diagram is 16, cf . Table 1 . In-cluding the YN FSI, i .e . possible conversion effectsEN AN, leads to a strong enhancement of thecross section in the A channel but only to a moderateenhancement in the E° channel . As a consequence,the resulting cross section ratio becomes significantlylarger than the value obtained from the Born termand, in fact, exceeds the experimental value . In caseof pion exchange the Born diagram yields a cross sec-tion ratio of 0 .9 . Adding the FSI increases the crosssection ratio somewhat, but it remains far below the
experiment.Thus, it's clean that, in principle, K exchange alonecould explain the cross section ratio - especially afterinclusion of FSI effects . However, we also see fromTable 1 that exchange is possibly the dominantproduction mechanism for the E° channel and there-fore it cannot be neglected . Indeed, the two produc-tion mechanisms play quite different rotes in the tworeactions under consideration, cf . Table 1 . K ex-change yields by far the dominant contribution forpp -+ pAK+ . The infiuence from 7r exchange is verysmall . In case of the reaction pp pE 0K+ how-ever, rr- and K, exchange give rise to contributions ofcomparable magnitude. This feature becomes veryimportant when we now add the two contributionscoherently and consider different choices for the rela-tive sign between the ir and K exchange amplitudes.In one case (indicated by "K + rr" in Table 1) ther and K exchange contributions add up construc-tively for pp --i- pE0K+ and the resulting total crosssection is significantly larger than the individual re-sults . For the other choice (indicated by "K - ir")we get a destructive interference between the am-plitudes yielding a total cross section that is muchsmaller . Consequently, in the latter case the crosssection ratio is much larger and, as a matter of facts,in rough agreement with the experiment (cf . Table1) suggesting a destructive interference between the7r and K exchange contributions as a possible expla-nation for the observed suppression of near-thresholdE° production.
Table 1 : Total cross section of the reactions pppAK+ (CA) and pp
pE°K+ (co) at the excessenergy Q 'rot 13 .0 MeV.
diagrams o-A [nb] o- E o [nb] -c-hA-s
K (Born) 706 45 16K (FSI) 2310 56 41
7r (Born) 68 76 0 .9(FSI) 109 103 1 .1
"K + ir" (FSI) 2360 247 9 .5"K -
(FSI) 2490 72 35
exp . [1] 505± 33 20 .1±3 .0 25±6
' also at : Inst . of Theoretical and Experimental Physics,117258, B .Cheremushkinskaya 25, Moscow, Russia'Nuclear Theory Group and INT, Dept . of Physics, Uni-versity of Washington, Seattle, WA 98195-1560, USA
References:[1] S . Sewerin et al ., Phys . Rev. Fett . 83, 682 (1999).[2] B . Holzenkamp et al ., Nucl . Phys . A500, 485 (1989).[3[ M. Hoffmann et al ., Nucl . Phys . A593, 341 (1995).[4[ M . Hoffmann, Jülich report, Ne . 3238 (1996).[5] M . Batinid et al ., Phys . Scripta 56, 321 (1997).
115
What is the structure of the Roper resonance?
0 . Krehl, C . Hanhart, S . Krewald, and J . Speth
116
The mass spectrum of excited baryon states is cal-eulated within several quark models [1, 2, 3] . Mostof these models have problems in describing the firstpositive parity resonance - the N* (1440), also calledRoper resonance, which lies in mass below the firstexcited states of negative parity . Different interactionmechanisms are made responsible for this change inthe level scheme and there is no consensus about thequestion : why is the mass of the Roper resonance sosmall [4]?
More information about the N* resonances can befound in photo- and electroexcitations . For the Roperthis has been studied by many groups [5] withoutcoming to a conclusion yet . Relativistic correctionsare found to be large, but whether the N* -yNtransitions have to be described in a q 3 model or ina hybrid q3g model remains unclear.The relativized quark model of Capstick et al . [2] wasextended to a calculation of the decay width of theN* resonance which results in an over-prediction ofthe N* (1440) rrN decay width . Furthermore theymention, that the importance of higher Fock states,such as q 4 q is unknown and has to be investigated.Although such investigations have been done in thestrange and charm sector [6], such an investigationis missing for the N* resonances . In summary, thestructure of the Roper resonance remains an openpoint in the quark models.
Analyses of experimental data on irN scattering aredone often in coupled channel resonance models [7]or K-matrix approximations [8, 9] . The resonancemodels do hardly allow for any kind of backgroundand therefore saturäte all structures by resonances.In contrast, the K-matrix approximation Ilses a mi-croscopical picture of the interaction based on phe-nomenological Lagrangians . This allows also for non-resonant mechanisms. However, the approximationsdone to a full coupled channel Lippmann-Schwingerequation are such, that a meson-baryon bound statecan not be described [10] . Therefore all poles of thescattering amplitude have to be provided as input.
Partial wave amplitudes as solutions of a full coupledchannel Lippmann-Schwinger equation up to ener-gies of 1 .9 GeV are missing . Our aim therefore wasto construct such amplitudes by extending the modelof Schütz et al . [11] to higher energies and more chan-nels . Our starting point is a phenomenological chiralLagrangian based on the one of Ness and Zumino[12] which is supplernented by additional terms forincluding additional degrees of freedom such as theA isobar or the 71 meson . This Lagrangian is usedin order to construct the interactions within andbetween the reaction channels rrN, crN, irA, pN, nN,and irN*(1520) . Of course the Lagrangian containsunknown coupling constants . But most of them arefixed or taken from other investigations. This leavesus with the cutoffs inside the formfactor (used to pa-
rameterize the size of each interaction vertex) as freeparameters . The so constructed interaction is theniterated in a coupled channel scattering equation.The resulting partial wave amplitudes are fitted toirN phase shifts and inelasticities, rrN
pN andirN ijN dass sections . Due to the fad that thenonresonant interaction mechanisms are contribut-ing to many partial waves, this fit constrains the pa-rameters very well [10] . Some partial waves are shownas an example in Fig . 1.
Phase shift (degree)
.21 .31 .41 .51 .61 .71 .81 .9
1 .1 1 .21 .31 .41 .51 .61 .71 .81 .9Z (GeV)
Z (GeV)
Fig. Some irN partial wave amplitudes comparedto data . The dashed line in the shows theresult of a fit using a separable irN, irA model.
The Roper resonance shows up as a resonant struc-ture in the partial wave amplitude L21 ,2j =where L(J) is the orbital (total) angular momen-tuni and 1 is the total isospin of the irN pair . Weare able to describe this partial wave without reso-nance contribution (i .e . without needing a genuine q3core) as good as many K-matrix models, which needsuch a q 3 resonance, as explained above . Instead, ourmodel generates the Roper resonance dynamically bya strong coupling to the reaction channel a'N, whichis a parameterization of a three particle state wherethe two pions interact in a relative S wave . Besidesthe rrA channel, which has a small contribution tothe P11, all other reaction channels are found to benegligible in this partial wave .
The reason for the a'N channel to be of that impor-tance can be found in the propagator
- E(E,q)
( 1 )
we are using for the quasi two particle propaga-tors . We have modified ehern by including a seif-energy term E, which takes the energy dependentmass shift and width of the unstable quasi particleinto account . Due to the very broad strueture in thescalar isoscalar 7r7r interaction, the threshold of theo'N channel is shifted down to 1 .3 GeV, where theinelasticity opens . The broadness of the r-ar structurereflects itseif in the steepness with which the inelas-ticity is rising . The rd channel is found to open athigher energies and much steeper . This is shown inFig. 1, where the dashed live is a fit using a sepa-rable 7rN,7r3, model and the propagator of eq . (1).Therefore the 7rN,7rd system does not allow for adescription of the as good as the 7rN, o-N sys-
tem.In order to find out more about the Roper resonance,we have calculated the speed in the Per which is de-fined by
SPIJL (E)
where r is the partial wave amplitude and E is thetotal energy. A resonant structure forms a peak in aplot where the speed is plotted against the total en-ergy of the system - the so called speedplot . lt doesso, because the speed is a measure for the time delayin the reaction and a large time delay is naturallyassociated with the formations of a resonance . Fur-thermore, we can extract parameters of the Roperresonance from heigth, center and width of the peakin the speedplot . Our speedplot is shown in Fig . 2.
Fig . 2 : Speedplot in the partial wave P . For com-parison also the speeplots of Höhler [13] areshown.
We have extracted the following parameters from thespeedplot:
rnR
1371 MeV,
= 167 MeV,
41 MeV .
where r is the modulo of the residue at the positionwhere 7- P 11 has a pole, mR is the mass and thewidth of the resonance . The phase of the residue islost in building the absolute value in eq . (2) . Thevalues for MR and F are in very good agreementwith other speedplot analyses done by Höhler [13].In addition, our values are also in agreement withthe pole positions of the VPI Group [8] . The residuer also agrees with the analyses mentioned before.Therefore we are able to describe the PIA as goodas many other analyses, but our investigation allowsfor an interpretation of the Roper resonance as dy-namically generated pole . Since the interaction be-tween nucleon and o- is found to be very strong inour model, we suggest a reanalysis of the N* spec-trum within the quark model where more attentionhas to be paid to meson-baryon intermediate statesand/or higher Fock states such as q 4 q.
References:
N. Isgur and G . Karl, Phys. Rev . D 18, 4187(1978) and Phys . Rev. D 19, 2653 (1979).S. Capstick and N . Isgur, Phys . Rev. D 34, 2809(1986).L .Ya. Glozman and D .O. Riska, Phys . Rep . 268,263 (1996).N . Isgur, LANL preprint nuclsth/9908028 ; L .Ya.Glozman, LANL preprint nucl-th/9909021.Z. Li and F .E . Close, Phys . Rev . D 42, 2207(1990) ; Z . Li, V. Burkert, and Z . Li, Phys . Rev.D 46, 70 (1992) ; S . Capstick, Phys . Rev . D 46,1965 (1992) ; S . Capstick and B .D . Keister, Phys.Rev. D 51, 3598 (1995) ; F. Cardarelli, E . Pace,G . Salmgravee, and S . Simula, Phys . Lett . B397,13 (1997) ; Y.B . Dong, K. Shimizu, A . Faessler,and A.J . Buchmann, Phys . Rev . C 60, 035203(1999).
[6] K . Maltman and S . Godfrey, Nucl . Phys . A452669 (1986) ; Fl . Stancu, Phys . Rev. C 58 111501(1998) ; M . Genovese, J .-M . Richard, Fl . Stancu,and S . Pepin, Phys . Lett . B425 171 (1998).R .E. Cutkosky and S . Wang, Phys . Rev. D 42,235 (1990) ; D .M . Manley and E .M . Saleski, Phys.Rev . D 45, 4002 (1992).
R .A . Arndt, I .I . Strakovsky, R.L . Workman, andM .M . Pavan, Phys . Rev. C 52, 2120 (1995) ; R .A.Arndt, R.L . Workman, 1 .I . Strakovsky, and M .M.Pavan, LANL preprint nucl-th/9807087 (1998).T. Feuster and U . Mosel, Phys . Rev. C 59, 460(1999) ; A .B . Gridnev and N .G . Kozlenko, Eur.Phys . J . A 4, 187 (1999).
[10] O . Krehl, C . Hanhart, S . Krewald and J . Speth,FZJ-IKP(TH)-1999-30 and nuclsth/9911XXX.
[11] C. Schütz, J . Haidenbauer, J .W . Durso, and J.Speth, Phys . Rev. C 57, 1464 (1998).
[12] J . Wess and B . Zumino, Phys . Rev . 163, 1727(1967) . 2671 (1994).
[13] G. Höhler and A . Schulte, 7tN Newsletter 7, 94(1992).
1
E
q2 + rnB
q2
(2)dr"L
dE
[7]
[8]
[9]
117
Coupled ehannel dressing of the nucleon
0. Krehl, S . Krewald, and J . Speth
The iteration of a nucleon pole diagram in aLippmann-Schwinger equation (LSE) - together withnon-pole background contributions leads to dress-ing of the nucleon . For the single channel case, thisis well understood and applied in many models ofe .g . 7rN scattering [1] . In an extended coupled chan-nel model of 7rN scattering, we found the couplingbetween the 7rN and o-N channel to be large [2].This should also influence the dressing of the nucleon.Therefore we have extended the dressing scheme usedin [1] to the coupled 7rN, o-N system. Other channelssuch as pN,7rd, and riN are found to have smallcontributions to the dressing and can be neglected.The potential (used as input in the LSE) can be di-vided into two parts:
v,,ß
vaPf3 +
( 1 )
where the pole part V2:,3 is of reparable form i .e V2:f3
fcOdoft30t and dj lE - m°N , (a, /3
Thepole part of the T-matrix is then determined by
TßPafßdfc, withd-1 =
dj l - E,E
E. f"Gc,fc,›
(2)fc,
+ Eß T«ßpGßfp° ,
ft
t + Eß f/30 G /3 TßNaP
where f (f » is the (bare) vertex function, d° (d) is thebare (dressed) propagator and E is the self-energy.The non-pole part of the T-matrix is still a solutionof the LSE
TNP _uNP + VNPG TNPßg
Following the arguments of Ref. [3] a relation be-tween dressed (gdr) and bare (g b ) coupling constantscan be derived:
g drgdr fßfl K
gb gb
nfgt
where K = (1 - E 1 ) - 1 ;
=
E(E)l„-:,„.In solving the coupled channel LSE for 7rN scatter-ing, the nucleon pole diagram is iterated togetherwith the non-pole part V NP of the potential . In or-der to ensure, that the dressing of the nucleon leadsto the physical mass and the physical coupling forE = rnN we have to use bare values for the nucleonpole diagram . The bare couplings is derived from Eq.(4) and the bare mass m 0 from the relation
rnN E(E
N
( 5 )
In solving Eq. (4) for the bare couplings attentionhas to be paid to the vertex functions f and theself-energy E, which still contain bare couplings ina nonlinear way. So we introduce vertex functionswhich do not contain any coupling constants :
:s-s
. With these, the coupled 7rN,o-N self-energy andgb
vertex functions read explicitly:
E
(gb ) 2 FR° tG,F2. + F,0, tG,(TiCG,F2)
+ (gb )2[FaOtG o, Fc, + F,2tGa ( To.o.PGun)
]
+ gb jF2tG, (T,,N,,PGa. )
+
Fa° tG, (T,N,PG,F2)] (6)
gb
arTo,NrP G
+ g TaN,7PG0 Fc?
,gg'
+ g ;'; P2
tG rirNar + gg'G aT,NorInserting these expressions into Eq . (4) results ina system of linear equations for the bare couplings(gg) 2 ,(gg) 2 and gb gb with coefficients, that containthe coupled non-pole T-matrix and the rrN and o-Npropagator . Solving this system determines the barecouplings . The bare mass is calculated using Eq . (5)and the self-energy from Eq, (6) . These are then usedin a calculation of 7rN scattering observables . Whenfitting experimental rrN data, the bare values haveto be determined each time, the parameters in thepotential have changed. Since we have changed thedressing scheme, which influences the partial wavePll, a re-fit is necessary . The re-fit of the partialwave P11 in the coupled channel 7rN, o-N, 7r3., pN, rjNmodel is shown in Fig . 1 . The parameters of this re-
Fig . 1 : Re-fit of the partial wave amplitude P11 in-cluding the coupled channel dressing of thenucleon.
fit differ from the ones where only the single channeldressing has been used . In order to get the attraction
90tl30.)
a) 60
t2 t3 1 .4
Z (GeV)
( 3 )
(4)
118
119
in the P11 at higher energies, the parameters of thefollowing diagrams have been changed [2]:
The 7r exchange contribution in the 7rN -4 o-N
transition potential has been enhanced by in-creasing the cutoff in the 7rlro- form factor toL2 GeV.
• The cutoff of the bare 7rNN vertex function inthe nucleon pole diagram has been lowered to1 .0 GeV.
• The cutoff of the bare o-NN vertex has beenChosen to be 1 .3 GeV.
• The cutoff at the o-NN vertex of the nucleonexchange diagram has been increased to 1 .8GeV.
The resulting bare parameters are:
0 .0777
(0 .0633)
19 .251010 .1 MeV (1032 .3 MeV).
The bare values from the single channel dressingscheme [2] are given in brackets . The dressed valuesare fixed to be f,2 NN ,/47r = 0 .0778 and g a2 NN /47r13 .0 at the nucleon pole (E = MN) [2].The additional inclusion of the o-N channel decreasesthe dressing of the bare rrNN coupling constant
( kfe = 0.95, was 0.8 in the single channel dress-f ih-ing scheme) . Also the bare mass of the nucleon issmaller, indicating, that dressing effects are weak-ened . The reason for this is not only the inclusion ofthe o-N channel into the dressing scheme, but alsothe smaller value ArNN 1 .0 GeV we have to usefor the nucleon pole diagram in the re-fit.After having determined the bare parameters in therefited mode!, Eq . (6) allows us to ca.kuhle thedressed vertex function . From this a form factor canbe determined as a ratio of dressed and bare vertexfunction properly normalized [4]:
Fdressed
f (p , z) f0 (P0)( p) z)
f0(p) f (po,z - rnN) «7)
where po is the an Shell momentum and .70 is thebare vertex function without form factor . The re-sulting dressed rrNN and uNN vertex functions areshown in Fig. 2 . Our rrNN vertex function can beparameterized by a monopole form factor
A2 m2
A 2 + i 2
with A 300 MeV (m = m 0.), which is a bit satterthan the vertex function found in the single ehan-nel dressing scheme of [4] . The importance of the7rN and o-N intermediate states can be judged byswitching ofl' the second and third term in the vertexfunction of Eq . (6), which leads to the dot-dashedand dotted curves in Fig . 2, respectively . These twocontributions cancel each other in such a way thatthe resulting dressed vertex function (solid line) is
0 .6
0 .5
0 .4zE11
N 0 .3CL
302
-0LL
0 .1
0
0 .8
0
p«GeV»
Fig. 2 : The dressed 7rNN and o-NN vertex functionsas a function of the momentum squared.
almost the saure as the bare vertex function (dashedline).Something similar can be see in the o,NN vertexfunction, where the 7rN and crN intermediate statecontributions cancel each other . This leads to a ver-tex function which differs hast muck from the barevertex function . lt can be parameterized using themonopole form factor from Eq . (8) with a cutoffA = 650 MeV and a mass m m, = 550 MeV.
References:
C. Schütz, J .W. Durso, K . Holinde, and J . Speth,Phys . Rev. C 49, 2671 (1994) ; A .L. Lahiff undI .R . Afnan, Phys . Rev . C 60 024608 (1999).
[2] C . Schütz, J . Haidenbauer, J .W. Durso, andJ . Speth, Phys . Rev. C 57, 1464 (1998) ; O.Krehl, C . Hanhart, S . Krewald, and J . Speth,FZJ-IKP(TH)-99-30 and nucl-th/9911080; O.Krehl, Berichte des Forschungszentrums JülichNo. 3692 (1999).B .C. Pearce and I .R. Afnan, Phys . Rev. C 34991 (1986) ; I .R. Afnan and A .T. Stelbovics,Phys Rev. C 23 1384 (1981) ; see also C.Schütz, Berichte des Forschungszentrums JülichNe, . 2733 (1993).
[4] C. Schütz, J . Haidenbauer, and K . Holinde,Phys. Rev. C 54, 1561 (1996) ; C . Schütz,Berichte des Forschungszentrums Jülich Na.3130 (1995).
(f°r )( g‹0,r,,iN l2
4ir0
vertex function-- manepole A=650 MeV
no aN intermediate stetes- - bare vertex function
-
no rd\l intermediate stetes
0 0 .5 1 .5
[3]
( 8 )
N , 13 (1520) : pN bound state or 3-valence-quark resonance?
0 . Krehl, S . Krewald, and J . Speth
In the last few years medium modifications of the pmeson have been investigated in heavy ion collisions[1] . Important contributions to a lowering of the massof the p in medium are found in the coupling of the pmeson to N*-hole pairs . Besides the coupling to theN*(1720), especially the coupling to N*(1520)-holestates plays an important role [2] . The reason for thiscan be found in the large branching fraction of thedecay (1520) -4 pN and therefore Zarge couplingto pN although phase space is small.Furthermore, photoabsorption experiments on nucleifound a large broadening of the N*(1520) in Boingfrom light to heavy nuclei . This effeet can be ex-plained when the medium modifications of the p me-son are considered [3].The structure of the N*(1520) can be understoodin two different types of models : quark models areable to describe the low lying negative parity states(such as the N*(1520) and the N*(1535) . Even ina simple minded nonrelativistic quark model with aconfining oscillator potential this resonance can beexplained as a single excitation of one quark [4] . Onthe other hand, investigations of the coupled trN/pNsystem in the partial wave D 13 found the N*(1520)to be generated dynamically as a pN bound state.This bound state is mahle possible by a large cou-pling between rrN and pN channel, the strong directpN interaction and the missing angular momentumbarrier of the pN S-wave state [5].In order to clarify this discrepancy, we have investi-gated the structure of the N* (1520) within a coupledchannel zrN, 7rA, o-N, pN model recently developedin Jülich [6] . We started this investigation by con-sidering only the partial wave D 13 . Indeed, in fittingthis data only, we were able to describe the N*(1520)as a pN bound state, where the rr exchange contri-bution in the rrN -4> pN potential generates a largecoupling between these two channels . The bindingenergy, i .e . the position of the resonance can be ad-justed by the strength of the p exchange contributionin the direct pN interaction. An interpretation as abound state is therefore obvious and the resultingdescription of the D 13 partial wave phase shifts andinelasticities is shown in Fig . 1 . However, in consid-ering other rrN partial wave amplitudes and, mostimportant, the -4 pN cross section, we found alarge disagreement between our model and the ex-perimental data . A fit to all rrN partial wave ampli-tudes and the rN -4 pN cross section does not alsIow for a dynamically generated resonance, becausethen the rN -4 pN cross section is overestimatedby an order of magnitude . The most important dia-gram for this cross section is the exchange in therN pN transition potential . Although it is pos-sible to cancel the strength of this diagram partlyin some partial waves by e .g . w exchange, the zt ex-change appears as the only contribution in the firm-
1 .0
1 .2
1 .4
1 .6
1 .8
Z (GeV)
Fig . 1 : The 7rN partial wave D13 . The dashed lineshows a dynamically generated N*(1520) res-onance. The solid line corresponds to the fitto many 2rN partial waves and the rrN -4pN cross section data including a genuineN*(1520).
sition rN( I D13 ) -4 pN(3S13 ) (notation : 2s L212j ),which builds up already 1/3 of the cross section . Theexperimental date( on this cross sections thereforeseverely constrains the parameters in the rN -4- pNtransition potential . This investigation shows, thatthe N*(1520) cannot be generated dynamically assoon as other observables have to be described at thesame time. This shows the importance of a combinedanalyses of many experimental data.
References:
[1] G .Q. Li, Ko, and G .E. Brown, Phys . Rev.Lett . 75, 4007 (1995) ; R. Rapp, G . Chanfray, andJ . Wambach, Nucl . Phys. A617, 472 (1997).
[2] G .E. Brown, G .Q . Li, R. Rapp, M . Rho, and J.Wambach, Acta Phys . Polon . B 29, 2309 (1998);
[3] R. Rapp, M . Urban, M. Buballa, and J.Wambach, Phys . Lett . B 417, 1 (1998) . W. Pe-ters, M . Post, H . Lenske, S . Leupold, and U.Mosel, Nucl . Phys. A632, 109 (1998).
[4] N. Isgur and G. Karl, Phys. Rev. D 18, 4187(1978) ; S . Capstick and N . Isgur, Phys . Rev. D34, 2809 (1986) ; L .Y . Glozman and D .O . Riska,Phys . Rep. 268, 263 (1996).
[5] R. Aaron, D.C . Teplitz, R.D . Amado, and J .E.Young, Phys . Rev. 187, 2047 (1969).
[6] O . Krehl, Berichte des ForschungszentrumsJülich No. 3692 ; O . Krehl, C . Hanhart, S . Kre-wald, and J . Speth, nucl-th/9911080.
200
150
100
0
120
Diffraction driven steep rise of spin structure function g LT = g l + 22 at small x and DIS sum rules
1 .Ivanov ' b , N .Nikolaev a‚ ', A .V .Pronyaev d , WSchäfer'
The combination gL T = g l -is 22 of spin structurefunctions of deep inelastic scattering (DIS) is relatedto the absorptive part of amplitude App, ,x ( = 0)of forward (T) transverse to (L) longitudinal photonscattering accompanied by the target nucleon spin-flip, o- LT ot
cx x2 g LT ( x , Q 2 ), where
is
the momentum transfer and Q 2 and x are standardDIS variables . lt has been a long standing beliefthat due to a number of reasons the correspondingspin asymmetry A 2 = 7 1, T /uT vanishes in small-x limit of DIS . For instance, the pQCD study ofsmall-x asymptotics of g 2 (x, Q 2 ) at the two-partonladder approximation showed the x-dependence typ .
-Mal of the low-lying reggeon exchange and the spinasymmetry A2 was indeed found to vanish in thesmall-x limit . A number of consequences of this be-havior include the Burkhardt-Cottingham (BC) andWandzura-Wilczek (WW) sum rules . The status ofthese results however has always been quite vaguedue to the presence of a number of assumptions be-hind them.We demonstrated that this behavior of g LT and A 2is not correct in the small-x domain [1] . We foundabout x-independent spin asymmetry A2 and scal-ing and steeply rising gLT (x, Q 2 ) at small x, and ex-pressed them in terms of experimentally measurablequantities . This leads to a glaring invalidation of BCand WW sum rules in their original formulation andmay affect even a phenomenological analysis of theexperimental da,ta.
Fig . 1 : The unitarity diagram with (a) `elastie' and(b) `inelastic' intermediate states
We found that there exists a unitarity or diffractivedriven contribution to gLT (x,C2.2 ) (hereafter all uni-tarity derived quantities will be supplied with su-perscript U) . Indeed, the one-pomeron exchangecontribution to Ami__ was proportional to A 2 ,thus vanishing in the strIctly forward case . How-ever such kinematical zeros can be lifted by unitar-ity corrections, the simplest example of which is atwo-pomeron exchange rescattering diagram (Fig . 1).Such a diagram has an extra loop and therefore canbe viewed as an integral of the product of two hon-forward single-pomeron exchange amplitudes, whoseexpressions are known . The LT transition occursin either of the diffractive '7* X vertices andspin-flip transition in either of the pomeron-nucleonvertices, the other two vertices are spin non-flipones. The both spin-flip transitions yield the fac-
121
tor (e t A) (ex [nA] ) , whose integration over azimuthalangle 0 of b yields a certain, non-zero value . The
general result for the unitarity driven g (uLT
) can beexpresed in terms of scaling and dimensionless LTdiffractive structure function gPT (xrp, Q 2 ) and theratio r5 of the proton-pomeron spin-flip to non-spin-flip coupling constants:
1g LWT) ( X , Q 2) = 2 r5(0 ) sin (7a1P)
d
BLT
D4m (BLT +B5)2 gLT (xlp , /3, Q 2
O1 )
where and xlp =
are standard diffractive DISvariables, B i are the effective diffraction slopes.Eq. (1) is our central and completely model inde-pendent result . In principle, both gfr and r 5 canbe measured experimentally. However, it is also in-tructive to perform some model calculations and ob-tain a numerical estimate. To do this, we accepteda heavy quark ansatz, in which the driving term ofdiffractive DIS is excitation of qq Fock states of thephoton, which dictates the relevant scale (2 of the or-der of the quark mass . The lower blobs in diagramsof Fig. 1 can be approximated by the conventionaldiagonal gluon density . The results reads:
Q2) 1 r5(0 ) asG 2 ( x e f f ,C 2 2 )
30x 2 (BLT + B5)22rn
(2)
For a numerical estimation of x 2gET (x,Q 2) wetook a conservative value r 5 = -0 .1 and obtained
(u)gLT (x, Q 2 )
10-5 (0 .001/x)04 , which correspondsto spin symmetry A 2 of order of 10' in the regionof x 10 -3 10 -4 and at moderate Q 2 . Comparingthis results with low-lying reggeon exchange calcula-tions, we deduce that for x < 0 .001 our diffractivemechanism takes over and asymptotically saturatesthe value of gLT .As we already mentioned, this dramatic rise of gLTcauses severe violations of the BC and WW sumrules . This breaking down is an emphatical demon-stration of non-universality of assumptions these re-lations are built on . Therefore these (and similar)relations must be at least reconsidered . Besides, ourresults have relevance to other issues, for example,to the accuracy in extraction of g l from longitudinalassymetry A 1 ." Institut für Kernphysik, Forschungszentrum Jülich,'Novosibirsk University, Novosibirsk, Russia
Landau Institute for Theor . Phys., Moscow, Russia4 Virginia Polytechnic University, USA
References:[1] I .P. Ivanov, N .N. Nikolaev, A.V . Pronyaev,
W. Schäfer, Phys .Lett . B457 (1999) 218-226;Phys .Rep . 320 (1-6) (1999) 175-186.
P
P
gLT( u )
The perspectives of study lightest sealar a o- (980) in the reaction pd ppao- p s close to threshold
V .Baru»b A .Kudryavtsev° b, v Tarasov b, v Chernysheva ' b
The study of lightest scalars fo(980)0+(0++) andao(980)1-(0++) is one of the most fundamentalproblem in physics of hadrons . _Both these mesonsare strongly coupled to the KK-channel and havepractically equal masses . We suggest to study fun-damental characteristics of ao- -meson by measuringits production cross section in nucleon-nucleon col-lisions, i .e . in the reaction pn -ei- ppao- . To studythis reaction we need to use deuterium target, i .e . tomeasure the reaction pd ppao-ps at Iow momentaof proton spectator p, < 250MeV/c . The privilegeof this reaction is that all final pahfieles may be iden-tified and measured . To reconstruct the kinematicsone need to measure all final protons in this reaction,i .e . both fast protons and proton-spectator . The de-cay mode a o- K- K° may be identified by mea-suring negative kaons and the mode a o- -sf n` r7 byrneasuring the decay 2-7 . In case of the reactionpn -+ ppa o- in the laboratory system dose to thresh-old all final particles are in a narrow cone aroundthe beam direction . The longitudinal momenta ofall particles (protons and ao) are of order of lGeVand the transverse momenta are small . For examplefor excess energy Q = 50MeV the maximal protonscattering angle is small, around 10° . The scatteringangles for and ir are not so small because of a Zargeenergy release in the decay ao -+ 1t77.
To estimate the production amplitude for the reac-tion pn -4 ppao- dose to threshold we use a sim-ple fusion model with intermediate ri- and fr-mesons.aomr-coupling is determined by the relation:
29a01r17
-----
8fr (1iri7
where qnn is rpr-relative momentuni . For bare partialwidth Ihr ,7 = 80MeV we get ga 0 = 2 .5 . We alsointroduce vertex formfactors and apply the antisym-metrization procedure in respect to the final protons.The expression for the total cross section also in-cludes the strong pp FSI effects and the finite widthof a o- . We took into account also the threshold de-pendence for ao KK-process . In Fig .1 we presentour predictions for the total cross sections of the re-action pn -+ ppao- for various intervakof integrationover effective mass of ao- : m,in < rhaa < rn,,na ,where rrnnini-h ao C, mr,, a , =
2m, - M ao
and C is a cutoff Parameter . The distributions for daare shown in Fig .2 at some fixed vorne of ratiodm,,,,
2gaK-K 0
d= 2g a o Ir-n
which taken to be 0 .91 according to [1], and typicalvalues of ao mass . As it follows from our preliminaryestimations, the differential cross sections are verysensitive to mass fhao and width F of ao-meson . A
Fig. 1 : Total cross section of the reaction pn --+ ppacaIculated at total width of ao equal to 50 MeVand various intervals of integration.
study of effective mass distribution gives a possibil-ity to determine these parameters . An analysis ofbranchings ratio
Br(ao -+ KK)
Br(ao
7t77)
would allow to extract ratio d (2) . If the experi-mental resolution in mass of ao-meson Am is about5MeV/c 2 one could extract the parameters of ao-meson with better accuracy, than it is known for to-day (see, e .g . [1]) . The interaction of ao with protonmay also be observed if it is not negligibly small (inGribov's [2] approach it is small) . Near the thresh-old both final protons and ao move slowly and there-fore the aop-interaction should give some infiuenceon aop- and pp-effective mass distributions.So, the proposed experiment could provide gettingan unique information on fundamental charaderissfies of ao-meson and its interaction with proton atIow energies.`Institut für Kernphysik, Forschungszentrum JülichGmbH, D-52425 Jülich, Germany°Institute of Theoretical and Experimental Physics,117258, B .Cheremushkinskaya 25, Moscow, Russia
References:[1] S . Teige et al . Phys.Rev .D, v .59, p .012001 (1998).[2] V.N.Gribov , LU-TP-91-7.
Usw]
Fig . 2 : Distribution over 7i-ihmass calculated at2629MeV, d=0.91.
( 1 )
(2)
122
Microseopie calculation of r/-meson production in the reaction NN -s+ NN?)
V. Bam' . J . Haidenbauer, J . Speth
There are already quite a few theoretical investiga-tions on the reaction NN -+ NNi) in the literature[1]-[6] (cf . Ref. [7] for an overview of the presenttheoretical and experimental situation) . Most of themodels are based on the calculation of tree level dia-grams like in Fig . 1 taking into account contributionsfrom the exchanges of various mesons . The maindifference between these models lies in the selectionof the exchanged mesons and in the construction ofthe corresponding MN rjN transition amplitude.With regard to the latter it is often assumed that thistransition occurs via the N*(Sn(1535)) resonance,as depicted in Fig. lb . Only in Ref. [4] a more re-fined model is used . In this work the MN -4 oN am-plitudes are generated from a multi-channel multi-resonance model, that was developed for describingthe
-+ irN and irN 4-> r7N data .
-----M
P
a)
b)
Fig . 1 : Diagrams for production. (a) One-bosonexchange contribution ; (b) One-boson exchangemechanism where the reaction Mp tw (M =ir, q, p, w, . . .) proceeds only via the excitationof an intermediate N*(1535) resonance.
All these models yield results that are in rough agree-ment wich the experiments . However, they differ sig-nificantly in the role played by the vector-meson (p,w) exchange contributions . Naturally, the results fie-pend strongly on the values used for the couplingstrength to the N* resonance (gNN.p, gNN.w) whichare not directly experimentally accessible . E .g., theNN*p coupling constant taken from vector mesondominance, adopted in Refs . [1, 2], is fairly largeand therefore it's not too surprising that p exchangewas found to be the dominant contribution in theseworks. On the other hand, Vetter et al . [3] deter-mined the p coupling constant from the N*(1535) -Np decay width, while the w coupling constant wasfixed by the relation gNN.,,gNN, = gNN.,gNNr.They find that the w-exchange plays a rather sig-nificant role . Finally, the model of BatiniC et al . [4]involves only the ir,ri and o--exchange contributions,i . e. no vector mesons at all, and is still able todescribe the data.
A further uncertainty in the presently existing mod-els comes from ambiguities in the relative phases be-tween the various meson exchanges . Basically those
phases are fixed by hand.Obviously there is still a strong need for a thoroughmicroscopic calculation of the reaction NN NNr).One of the pre-requisites for such a calculation is amodel in which all the elementary reaction ampli-tudes MN --+ r7N that enter into the o, productionamplitude (cf. Fig 1) are treated in a consistent way.Such a model has been presented recently by theJülich group [8] . lt is a coupled channel model ofthe irN system developed for studying the structureof the excited states of the nucleon . lt contains ex-plicitly the channels irN, pN, 1)N, rrN*(1520), oN,and 7rA . The interactions in and between the variouschannels are derived in the meson-exchange picturestarting out from effective Lagrangians . Most of thecoupling constants at the meson-baryon-baryon andmeson-meson-meson vertices are taken from othersaurees. The cutoff massec at the vertex form factorsare the only free parameters which were determinedby a fit to the irN partial-wave amplitudes . The re-sulting model yields a satisfactory description of theavailable irN phase shifts and inelasticities from the
threshold up to energies of about 1 .9 GeV as wellas of the irN -4 i-/N and irN > pN transition crosssections [8].Thus, this model provides an excellent starting pointfor a consistent microscopic investigation of the re-action NN --+ NNri . lt should enable us to drawmore reliable conclusions on the infiuence of the var-ious meson exchanges an rl production . Specifically,we believe that the role played by the vector-mesonexchange can be clarified. Furthermore, we wantto emphasize that within this model also all rela-tive phases between the various contributions to theproduction amplitude are fixed . This allows us alsoto address the question of the cross section ratio
Hein most of the presently avail-able models seem to have difficulties in reproducingthe experimentally observed large value [9].
'also at : Institute of Theoretical and ExperimentalPhysics, 117258, B .Cheremushkinskaya 25, Moscow, Rus-sin
References:[1] J .-F . Germont, C . Wilkin, Nucl . Phys . A518, 308
(1990).[2] J .M. Laget et al ., Phys . Lett . B 257, 254 (1991).[3] T. Vetter et als, Phys . Lett . B 263, 153 (1991).[4] M. Batinid et als, Phys . Ser . 56, 321 (1997).[5] E. Gedalin et ad ., Nucl . Phys . A634, 368 (1998).[6] A.B. Santra and B.K. Jain, Nucl . Phys . A634, 309
(1998).[7] H . Machner and Haidenbauer, J . Phys . G 25, R231
(1999).[8] 0 . Krehl, Jülich-Report Jü1-3692 (1999) ; 0. Krehl et
ah, nucleth/9911080.[9] H . Calen et ah, Phys . Rev . C 58, 2667 (1998).
P
M
123
Photon-Photon and Photon-Hadron Physics in Relativistic Heavy Ion Collisions
G . Baur, K . Hencken*, P . Stagnoli*, and D . Trautmann*
In central collisions at relativistic heavy ion col-liders like RHIC at Brookhaven and LHC atCERN/Geneva one aims at producing and detect-ing a new form of hadronic matter, the Quark GluonPlasma . lt is the purpose of [1] to discuss a comple-mentary aspect of these collisions : the very periph-eral ones . Due to coherence there are strong electro-magnetic fields of short duration in such collisions.They give rise to photon-photon and photon-hadroncollisions up to invariant mass regions hitherto un-explored experimentally.The Relativistic Heavy Ion Collider RHIC will soongo into operation in Brookhaven . A dedicated pro-gram exists to study these peripheral collisions [2].A theoretical review was given at PHOTON 99 [3].lt is expected that first resuits will be presented atPHOTON 2000 in Lancaster, see p .11 of [4].Recently it was suggested to use the CMS detectorat LHC for photon-photon physics at LHC [5] . Someaspects of this were discussed in detail in connectionwith the Letter of Intent for FELIX [6].These relativistic heavy ion colliders may also servewell as vector meson factories. This is discussed in[7, 1] . A new energy regime will be entered at LHC.At RHIC the invariant mass region is similar to theone at HERA.Calculation of higher order effect in electron-positronpair production in relativistic heavy ion collisionshave recently been done in [8] . Whereas the single-pair production cross section is mainly unaffected bythese higher order effects, cross section for multiplepair production were found to be rather sensitive.Production of Iow mass electron pairs due to thephoton-photon mechanism in central collisions wasrecently studied theoretically in [9] . This is a poten-tial background to more interesting mechanisms . Wefind that this mechanism is negligible for the condi-tions of the GERES experiments [10].Detailed studies of dielectron production in pe-ripheral relativistic collisions were recently done in[11, 12], where also large transverse momenta pl ofelectrons or positrons are considered . This is also anupdate of the work of [13] . Exact calculations arecompared to calculations using the equivalent pho-ton approximation . In addition to the peak due tothe equivalent photon mechanism, where the
dis-tribution is peaked for , we find an ad-ditional peak where one of the p is small and theother large . This second peak can be attributed tothe "equivalent electron mechanism" [14].
References:
[1] G . Bam. , K . Hencken and D . Trautmann, Top-cal Review > Journal of Physics G24 (1998) 1657.
[2] Star Peripheral Collision group, see, e .g ., athttp ://www .star .bnl .gov/STAR/html/pec1
124
/base .html.
[3] K . Hencken, P. Stagnoli, D . Trautmann, andG . Baur, "Photon-Photon arid Photon-HadronPhysics at Relativistic Heavy Ion Colliders" , toappear in "Proceedings of Photon°9 g ' , Freiburg,May 23-27, 1999, edited by S . Söldner-Rembold.
[4] CER,N COURIER Vol .39 . September 1999.
[ 5 Baur, K . Hencken, D. Trautmann, S.Sadovsky, and Yu . Kharlov, "Photon-PhotonPhysics with heavy ions at CMS" , CMS Note1998/009 (1998), available from the CMS infor-mation server at http :/cmsserver .cern .chand "Coherent Interactions with heavy ionsat CMS" , contribution to the CMS HeavyIon Chapter, in preparation, hep-ph/9904361(1999).
[6] FELIX Letter of Intent, CERN/LHCC97-45.LHCC/I10 (1997).
[7] S. R. Klein and J . Nystrand, Phys . Rev . C60(1999) 014903.
K . Hencken, D . Trautmann, and G . Baur, Phys.Rev . C59 (1999) 841, nucl-th/9808035.
K . Hencken, D . Trautmann, and G . Baur, to bepublished in Phys . Rev . C, hep-ph/9908448.
[10] G . Agakichiev et al . Phys . Rev . lieft . 75 (19951272.
[11] P. Stagnoli, "Differentielle Wirkungsquer-schnitte und p_L -Verteilungen für e + e7 -Paar-produktion in peripheren ultrarelativistichenSchwerionenkollisionen" , Diplomarbeit U Basel(1999) (unpublished).
[12] P. Stagnoli, K . Hencken, G . Baur, and D.Trautmann, "Differential cross sections forQED dielectrons production at relativistic heavyion collisions" abstract submitted to QuarkMatter '99 . 1999.
[13] N. Baron and G . Baur, Phys . Rev. D46 (1992)R3695.
[14] M .Chen, P .Zerwas, Phys .Rev .D12 (1975)
*Institut für Theoretische Physik, Universität Basel,Klingelbergstrasse 82, CH 4056 Basel, Schweiz
[8 ]
[ 9 ]
A Novel Mechanism For Bremsstrahlung in Relativistic Heavy Ion Collisions
K . Hencken*, D . Trautmann*, and G . Baur
The present work is published in [1] . A novel mech-anism for bremsstrahlung in peripheral relativisticheavy ion collisions is described.The cross-section for electron-positron pair produc-tion in relativistic heavy ion collisions is huge, see,e .g ., [2] for a general reference . On the other hand,bremsstrahlung in peripheral relativistic heavy ioncollisions was found to be small, both for real [3]and virtual [4] bremsstrahlung photons . This es-sentially due to the large mass of the heavy ions.Since the cross section for e + e- pair production isso large, of the order of 100 kb for RHIC and LHC,one can expect to see sizeable effects from the radia-tion of these light mass particles . In the soft photonlimit (see, e .g ., [5]) we can calculate the cross sectionfor soft photon emission of the process as
Z + Z Z + Z + e + + e +7
as2
p-
p+p+k
d sk
x 4ir 2 w d (7 0 (P+ ' P- )
where do-o devotes the cross section for the e + e -pair production in heavy ion collisions . Using ourcode [6] for the e + e - pair production we can cal-culate the soft photon emission from the outgoinglepton lines numerically according to this equation.An alternative approach is done by using the DEPA(double equivalent photon approximation) and calcu-lating the exact lowest order matrixelement for theprocess
y± y-4 e+ -Fe- ±y.
In fig .1 we show results of such a calculation for lowenergy photons.These low energy photons constitute a backgroundfor the detectors . Unlike the low energy electrons andpositrons, they are of course not bent away by themagnets . Recently the soft bremsstrahlung photonsfrom central ultrarelativistic nucleus-nucleus colli-sions were suggested to be used to infer the rapiditydistribution of the outgoing charge [7] . We note thatthe presently considered soff, photons from periph-eral collisions can be a source of background for theconsidered experiment.
References:
[1] Hencken, D . Trautmann, and G . Baur,Phys . Rev . C60 (1999) 034901 . see also nucl-th/9903019.
[2] G . Baur, K . Hencken and D . Trautmann, Topi-cal Review, J . Phys . G24 (1998) 1657.
[3] C . A . Bertulani, G Baur . Phys . Rep. 163 (1988)299 .
Figure
1 :
The
cross
section
da-/dQclchfor bremsstrahlungsphotons for Au-An collisions at,RHIC are shown as as a function of the photon en-ergy and for different angles (1, 10, 30, 90 0 from topto bottom) ;three different approximations are used,for details see [1].
[4] H. Meier, K . Hencken, D . Trautmann, andG . Baur, Pur . Phys . J . C2 (1998) 741.
[ 5 ] S . Weinberg, "The Quantum Theory of Fields"Vol . 1, 1995, Cambridge.
[6] A . Alscher, K . Hencken, D . Trautmann, andG . Baur, Phys . Rev. A55 (1997) 396.
[7] S . Jeon, J . Kapusta, A . Chikanian, andJ . Sandweiss, Phys . Rev . 058 (1998) 1666.
*Institut für Theoretische Physik Universitaet Basel,Klingelbergstrasse 82 CH4056Basel Schweiz
du ( k iPeiP+) =
r
-e 2
125
Bound-Pree Pair Production in Relativistic Heavy Ion Collisions
H . Meier*, Z . Halabuka*, K . Hencken*, D . Trautmann*, and G . Baur
We study the electron-Positron pair production withelectron capture to the K- and higher shells in rel-ativistic heavy ion collisions . For a general referencesee [5] . The bound-free pair production in the colli-sion of two charged particles has found an applica-tion in the production of relativistic antihydrogen [1].The corresponding process will be very important atthe forthcoming relativistic heavy ion colliders RHICand LHC. Due to the change of the charge to massratio in the capture process
Z+Z->Z+Z+e++e
( 1 )
the ions will be lost in the circulating beam andthe luminosity will be seriously affected . lt is im-portant to know the cross section very accurately.In [2] and [3] the bound-free pair production lead-ing to relativistic antihydrogen was calculated in thePWBA . 'VVhereas in the latter reference lepton wave-functions appropriate for the low values of Z (= +1and -1)were used, we use now [6, 4] exact Dirac wavefunctions .They are also valid for the higher Z-valuesof the relativistic heavy ions . we find that the crosssection can be written as
o- B + A log 8 .
(2)
In table 1 the values of A and B for various ions aswell as final atomic orbits are given . In Fig . 1 weshow our results for pair production with e-captureinto the K-shell . For further details see [6] . There is
200
180
160
140
120
--e.
100
6 80
60
40 [
20 [
0 i1
Figure The cross section o- Isfor .K-shell bound-freepair production in an Au-Au collision is shown as afunction of the Lorentz factor -y in the collider refer-ence frame.
an 1/n3 scaling law for the s-states Transitions to pstates is strongly supressed . Due to the s-characterof the small , -oinponent of the p1/2 wave function, itis enhanced as compared to the p3/2 wave function.We eagerly wait for the experimental results fromRHIC.
Referencesi
[ 1 ] PS21 collaboration, W . Oelert, spokesperson, G.Baur et al ., Phys. Lett . B368 (1996) 251.
[2] H . Meier, Z . Halabuka, K . Hencken, D . Traut-mann, and G . Baur, Eur . Phys. J . C5 (1998)287, see also hep-ph/9712461.
[ 3 ] C . A . Bertulani and G . Baur, Phys . Rev. D58(1998) 034005.
[4] H . A. Bethe and E . E . Salpeter, Quantum Me-chanics of One- and Two-Electron Atoms, 1977,Plenum Publishing Corporation, New York.
[ 5] G . Baur, K . Hencken, and D . Trautmann, Top-ical Review, J . Phys . G24 (1998)1657.
[6] H .Meier et al . to be published
*Institut für Theoretische Physik Universitaet Basel,Klingelbergstrasse 82 CH4056Basel Schweiz
0' 2s 6 .70 . 10-13 _4 .23 . 10 -137 .73
10-18 -5 .20 - 10 -180-2p(l/2)
3 .10
10 -18 -2 .42 . 10 -18(72p(3/2)
'573s 1 .98 . 10- 13 -1 .26 . 10' 3'Ca-Ca 0 1s 3 .84
10-2 .4810-30-2s 4.78
10 -4 -3 .07
10'
0 2p(1/2) 3 .35
10 -6 -2 .33 . 10'
0 2p(3/2) 9.02
10- 7 -7 .27
10- 7O'3s 1 .41
10- 4 -9.10
10- 54 A''7
j-1 1".i 7 Ag a ls 8.68
10 1 -5.6310-10-Cr2s 1 .07
10 -11 .07 -6.94 . 10-2CT 2p(I/2) 7.05
10 -3 -5.02 . 10-30- 2p(3/2) 9.87
10-4 -8.31 . 10
4O-3s 3 .13
10 -2 -2.02 . 10 -279 Au_ 79 Au 0'1s 2.38 10 -1 .47 . 10
0-2s 3 .04 -1 .87
0- '4(1/2) 9 .2710 -110 -1 -6.56.10 - 'PO'0- 2p(3/2) 5 .62 . 10- 2 -4.93 . 10-2
g3s 8 .67 - 10 -1 -5 .34 . 10-'82Pb-82 Pb a ls 3 .04 , 10 -1 .87
10 1O'2s 3 .91 -2 .39
0i 2p(1/2) 1 .34 -9 .46 . 10 -17 .50 . 10- 2 -6 .61 . 10- 20'2p(3/2)
O-3s 1 .11 -6 .79
10'92u_92u 6 .60
10 -3 .90 . 100i2s 8 .63 -5 .10
c7 2r81/2i 4 .30 -3 .000- 2p(3/2) 1 .83
10 -1 -1 .63
10 -0-15 2 .43 -L44
Table 1 : Cross section and parameters A and B aregiven for different ion-ion collisions.
10
100
1000
10000
Y
ion-ion
o-
A[b]
B [b]
1H- 1 H
0' ls 5 .36 . 10-12
-3 .40 . 10 - 12
126
Pionium interacting with matter
T .A . Heim*, K . Hencken*, D . Trautmann*, and G . Baur
We present results of a detailed investigation ofthe target-elastic and target-inelastic electromag-netic cross sections for pionium scattering off varioustarget materials . Further details can be found in [1]and [2] . Accurate predictions for there cross sectionsare needed as a theoretical Input in the analysis ofthe on-going DIRAC experiment at CERN [2] . Thisexperiment aims at measuring the pionium lifetime,an important check on chiral perturbation theory [2].Within the ciosure approximation [3] the total elec-tromagnetic cross sections from a given pionium ini-tial state i can be written as
2
tot = 16ir (a
.Ire dq~ q1 (I'A ( k ) (1
A(s)) (1)
where the momentuni transfer variables s and k re-fer to the liest frame of the pionium and the atom,respectively. gi denotes the monopole formfactor forthe pionium in the state For the target-elastic to-tal cross section the atomic structure is given by4 A (k) = (Z - Foo(k)) 2 , where Foo denotes the co-herent formfactor of the electronic ground state or-bitals only, as the contribution from the (point-like)nucleus has been separated out . We calculate theatomic formfactor in the framework of the Dirac-Hartree-Fock-Slater model, i .e ., using orbitals ob-tained from the numerical solution of the Dirac(or Schrödinger) equation for each occupied orbital.However, the coherent formfactor is very well approx-imated by simple analytical expressions as given byMofiere or Salvat et al . [4].In the rase of the target-inelastic total cross section,the atomic structure is contained in nli A (k) = Sin ,(k).We determine Sin , using the same orbitals as forthe coherent formfactor . In a simple "no-correlationlimit", Sin ,(k) Z - [Foo(k)]2/Z . This approxi-mation is not sufficiently accurate, as it completelyneglects Pauli blocking and thus over-estimates thecross section . Our approach with Dirac-Hartree-Fockorbitals correctly accounts for Pauli blocking inSine(k) . Moreover it affords determining the contri-butions to the pionium cross sections for each atomicShell individually. This information cannot be ex-tracted from tabulated values of formfactors andscattering functions [5] where only the combined con-tributions of all atomic shells are given.The diagram shows the integrand of (1), multipliedwith the integration variable ql (thus representingmore clearly the relative magnitude of the individualcontributions to the integral on a logarithmic scalefor u) . The target material is Ti (Z = 22), pioniumis initially in its ground state . Note that the choiceof atomic excitation energy A affects the integrandonly at qi smaller than the range of dominating con-tributions . The main contributions to the integralcome from a complex interplay of photon propagator,
Integrand for cross sections ; Ti target, Pionium isbiegrand weeteef wich
targebblefastio by shebqi;
q, [a . .]
atomic, and pionium structure at 1 < ql < 100 am.Note also that the outer shells contribute much moreto the target-inelastic cross section than the innershells . Not only are there more electrons in outershells than in inner shells, but the contribution ofeach individual target electron is approximately pro-portional to its principal quantum number. Finally,note that the target-inelastic cross section is signif-icantly larger than the target-elastic divided by Z.Thus neither the "no-correlation" limit, nor the sim-ple scaling approximation otn~ cr, oh /Z are accurateenough.
References:
[1] T. Heim, K. Hencken, D. Trautmann, and G.Baur, to be submitted to J. Phys. B
[2] Proceedings of the Workshop on HadronicAtoms ("HadAtom99") held in Bern, October14-15, 1999 (J . Gasser, A . Rusetsky, and J.Schacher, eds .) published in : hep-ph/9911339
HaJabuka, T .A . Heim, K . Hencken, D . Traut-mann, and R.D . Viollier, Nucl . Phys . B554(1999) 86.
[4] F. Salvat et al ., Phys. Rev . A36 (1987) 467;G . Moliere, Z. Naturforsch . 2a (1947) 133.
[5] J .H. Hubbell et al ., J. Phys . Chem. Ref. Dato 4(1975) 471 ; ibid . 6 (1977) 615 ; J .H. Hubbell and1. Overbo, ibid . 8 (1979) 69.
* Institut für theoretische Physik, Universität Basel,Klingelbergstrasse 82, CH-4056 Basel, Switzerland
127
Coupled channel dressing of the nucleon
0. Krehl, S . Krewald, and Speth
The iteration of a nucleon pole diagram in aLippmann-Schwinger equation (LSE) - together withnon-pole background contributions leads to dress-ing of the nucleon . For the single channel case, thisis well understood and applied in many models ofe .g . 7rN scattering [1] . In an extended coupled chan-nel model of 7rN scattering, we found the couplingbetween the 7rN and channel to be large [2].This should also influence the dressing of the nucleon.Therefore we have extended the dressing scheme usedin [1] to the coupled 7rN, aN system. Other channelssuch as pN,7rA, and 1)N are found to have smallcontributions to the dressing and can be neglected.The potential (used as input in the LSE) can be di-vided into two parts:
v,ß = v:ß + vo,NßP ,
where the pole part
is of separable form i .e 17,ß =7-
fa°do fß0t and dj l = E - m°N , (a, /3 E f7r,ul) . Thepole part of the T-matrix is then determined by
TßPe,
d- =E
ae.
where f (f°) is the (bare) vertex function, d° (d) is thebare (dressed) propagator and E is the self-energy.The non-pole part of the T-matrix is still a solutionof the LSE
TNP vNP + EvNP TNPß a
f3a
ih "'r i gg
Following the arguments of Ref . [3] a relation be-tween dressed (gdr ) and bare (g b ) coupling constantscan be derived:
g (cirg ,ßir
f,3f. K9bgb
f12fgt
where K = (1 - E 1 )-1 ; +- 4 E (E)lE=rnN .In solving the coupled channel LSE for 7rN scatter-ing, the nucleon pole diagram is iterated togetherwith the non-pole part V NP of the potential . In or-der to ensure that the dressing of the nucleon leadsto the physical mass and the physical coupling forE = MN we have to use bare values for the nucleonpole diagram. The bare couplings are derived fromEq. (4) and the bare mass m° from the relation
= mN - E(E =-
In solving Eq. (4) for the bare couplings attentionhas to be paid to the vertex functions f and theself-energy E, which still contain bare couplings ina nonlinear way. So we introduce vertex functionswhich do not contain any coupling constants :
:=--
-=-f . With these, the coupled 7rN, aN self-energy andg i'vertex functions real explicitly:
E
( gir )2 F2tG irF7r + F7r tG ir (r7rirPa,rF)
+ (gb )2Fa,OtG,Fcr + Fos tGo.(eiG,F,0)
+ g b [TVG, (Tiv:. 0.PGb,12)
+ F2 t G b.(Ta.NirPG,F2)] (6)
96 Fa + g"br Tc,N7,rG b-F,2 + gb',T,,,No.PG,F,,?,gg'F2t + gjF,2 t G,T,No,P + gjeG,To. aP .
Inserting these expressions into Eq . (4) results ina system of linear equations for the bare couplings(gj) 2 ,(gg) 2 and g'br g7, with coefficients that containthe coupled non-pole T-matrix and the gN and aNpropagator . Solving this system determines the barecouplings . The bare mass is calculated using Eq . (5)and the self-energy from Eq . (6) . These are then usedin a calelilatim of 7rN scattering observables . Whenfitting experimental 7rN data, the bare values haveto be determined each time, the parameters in thepotential have changed. Since we have changed thedressing scheme, which influences the partial wave
a re-fit is necessary. The re-fit of the partialwave in the coupled channel 7rN, aN, asd, pN, r1Nmodel is shown in Fig . 1 . The parameters of this re-
Fig. 1 : Re-fit of the partial wave amplitude P11 in-cluding the coupled channel dressing of thenucleon.
fit differ from the ones where only the single channeldressing has been used . In order to get the attraction
fß.dfj,, withdj 1 - E,
La fc?, t Gafa,E 7,NPn i0
fat
ß -. ag ,'Orp,+ Eß A'GoeP .
(2)
( 3 )
(4)
90a)o)a.) 60
0
1 .0
1 .1
1 .2
1 .3
1 .4
Z (GeV)
128
0 .4z
E11
N 0 .3ffi
::'"'1
0 .2
U...
0 .6
0 .5
0.,
in the
at higher energies, the parameters of thefollowing diagrams have been changed [2]:
• The 7r exchange contribution in the 7rN -4 aNtransition potential has been enhanced by in-creasing the cutoff in the 7rzro- form factor toL2 GeV.
• The cutoff of the bare 7rNN vertex function inthe nucleon pole diagram has been lowered to1 .0 GeV .
aNN vertex function
vertex function- - monopole A=650 MeV no
intermediate states-- bare vertex function
no
intermediate states
• The cutoff of the bare rrNN vertex has beenchosen to be 1 .3 GeV.
• The cutoff at the ciNN vertex of the nucleonexchange diagram has been increased to 1 .8GeV.
The resulting bare parameters are:
0 .0777
(0 .0633)
19 .251010 .1 MeV (1032 .3 MeV).
The bare values from the single channel dressingscheme [2] are given in brackets . The dressed valuesare fixed to be f2NN /4zr = 0 .0778 and g2rNN /47t =13.0 at the nucleon pole (E mN) [2].The additional inclusion of the
channel decreasesthe dressing of the bare 7rNN coupling constant
f( 1 = 0.95, was 0.8 in the single channel dress-ing scheme) . Also the bare mass of the nucleon issmaller, indicating that dressing effects are weak-ened. The reason for this is not only the inclusionof the (IN channel into the dressing scheme, but alsothe smaller value A, NN = 1 .0 GeV we have to usefor the nucleon pole diagram in the re-fit.After having determined the bare parameters in therefited model, Eq. (6) allows us to calculate thedressed vertex function . From this a form factor canbe determined as a ratio of dressed and bare vertexfunction properly normalized [4]:
Fdressed
Z)
P(p, z)
f (po)
f°(p ) f (Po, z mN)
(7)
where po is the Shell momentum and is thebare vertex function without form factor . The re-sulting dressed 7rNN and o:NN vertex functions areshown in Fig. 2 . Our 7rNN vertex function can beparameterized by a monopole form factor
A2 m 2
A 2 + '1'2
with A = 300 MeV (m = mir ), which is a bit softerthan the vertex function found in the single chan-nel dressing scheme of [4] . The importance of thezrN and aN intermediate states can be judged byswitching off the second and third term in the vertexfunction of Eq . (6), which leads to the dot-dashedand dotted curves in Fig . 2, respectively. These twocontributions cancel each other in such a way thatthe resulting dressed vertex function (solid line) is
0 .8 .
7tNN vertex function
(GeV2)
Fig . 2 : The dressed 7rNN and (INN vertex functionsas a function of the momentum squared.
almost the same as the bare vertex function (dashedline).Something similar can be see in the (INN vertexfunction, where the 7rN and o-N intermediate statecontributions cancel each other . This leads to a ver-tex function which differs not much from the barevertex function . lt can be parameterized using themonopole form factor from Eq . (8) with a cutoffA = 650 MeV and a mass m = m, = 550 MeV.
References:
[1] C. Schütz, J .W. Durso, K. Holinde, and J . Speth,Phys . Rev. C 49, 2671 (1994) ; A.L. Lahiff undI .R. Afnan, Phys . Rev. C 60 024608 (1999).
[2] C. Schütz, J . Haidenbauer, J .W. Durso, andJ. Speth, Phys. Rev. C 57, 1464 (1998); 0.Krehl, C . Hanhart, S . Krewald, and J. Speth,FZJ-IKP(TH)-99-30 and nucl-th/9911080 ; 0.Krehl, Berichte des Forschungszentrums JülichNo. 3692 (1999).
[3] B .C . Pearce and I.R. Afnan, Phys . Rev. C 34991 (1986); I.R. Afnan and A .T. Stelbovics,Phys Rev. C 23 1384 (1981) ; see also C.Schütz, Berichte des Forschungszentrums JülichNo. 2733 (1993).
[4] C. Schütz, J . Haidenbauer, and K . Holinde,Phys. Rev . C 54, 1561 (1996) ; C . Schütz,Berichte des Forschungszentrums Jülich No.3130 (1995) .
vertex function--- manepole A=300 MeV--ei- no oN intermediate stetes- - - bare vertex function--- no aN intermediate stetes
(8)
0
129
The GAMS-BNL puzzle
Z. Wang, S . Krewald, and J . Speth
The GAMS and the BNL collaborations have provideda wealth of new experimental results on two-meson in-teractions via the pion-proton reaction . There is a puzzleconcerning the S-wave interaction of two neutral pions.in the n~-p reaction, at a primary pion momentum of 38GeV/c, the GAMS collaboration finds a dip in the S-waveat two-pion massec of about 1 GeV for small momentumtransfers( Itl < 0.2(GeV/e) 2 } . With increasing momen-tum transfer, the dip is rapidly filled and a narrow peakemerges for t j
0.3(GeV/c) 2)(Fig .1) . A similar effectis seen in the BNL data which were obtained with a pri-mary pion momentum of 18 .3 GeV/c . The peak has beeninterpreted as a hard component of the (980)mesonwhich would invalidate the interpretation of this mesonas a KK molecule [1].
Fig . S-wave contribution to ir 7T 0 production as a function of the invariant two-pion mass, for a primarypion momentum of 38 GeV. Data: GAMS collab-oration. Thick line : Theory with rr and d ie Thinline : ir only.
In the standard analysis of these reactions, one assumesa peripheral reaction mechanism, i .e . the incoming piononly interacts with a virtual pion emitted by the proton.For larger momentum transfers, the assumption of an ex-tremely peripheral reaction may no longer hold . In thepresent meson-exchange mode!, the exchange of a virtual
meson has been added to the virtual pion exchange .
130
Fig . 2 : S-wave contribution to ,n-°ir 0 production as a tune-tim of the invariant two-pion mass, for a primarypion momentum of 18 GeV. Data : BNL E852.Thick line : Theory with 7T and a I . Thin line : 7T
only.
Meson theory gives a simple explanation for the appear-ance of a dip . Below the threshold, pion-pion scat-tering is dominated by the exchange of a rho-meson in thet-channel . This is an attractive interaction which causes arapid rise of the phase shift resulting in a negative signof the reaction amplitude . At the threshold, an inter-ference effect with the transition to the opening channelreduces the eross section.The appearance of the bump can be linked to the fact thatthe virtual pion and the virtual do not interfere. Forlarge proton energies, the pion mainly induces a spin-flip,whereas the a l does not.A partial wave analyses of the GAMS and the BNL datasuggest at least five scalar resonances in the energy re-gion up to 1780 MeV. The present ealeulation is basedon the two-pion interaction of the Jülich model which in-cludes only one scalar resonance at 1500 MeV . For en-ergies above 1 GeV, a detailed agreernent of the presenttheory with the data may therefore not be expected.
References:
[1] Yu.D.Prokoshkin, Phys .At .Nuc162, (1999) 356.
000
8v 2
900
1000 1100
m,.,„ [MeV]
800
'CLE
-aiCTURE AND RE TIONMECi .
132
No missing isoscalar monopole strength in "Ni : final results ?
S .K amerdzhiev*, J .Speth, G .Tertychny*
The problem of missing IS E0 strength in 58Ni hasbeen discussed since 1996 [1, 2, 3, 4, 5, 6, 7, 8] . lt wasinitiated in Ref . [1] where only 32% (at best <50%)of the IS EO EWSR was observed in the (12 .0 - 25 .0)MeV excitation region . Therefore, the resonancemean energy might be changed strongly as comparedwith the value given by known systematics . Becausethe IS E0 resonance in fact gives the unique informa-tion about incompressibility of nuclear matter, thisproblem could have serious consequences for astra-physics and cosmology.Sambier and Khoa [3] reanalyzed the experimentalresults [1] using a refined (a, a» reaction descriptionand obtained 50% of the EWSR. In Ref . [3] as wellas in Ref. [1] the phenomenological transition densi-ties have been used to construct the EL transitionspotentials.Our calculations [2, 4], where microscopic transi-tion densities have always been used, give 71 .4%of the IS EO EWSR in the (12 .0-25 .0) MeV inter-val. The microscopic model used takes into ac-count all three known mechanisms of giant reso-nance damping, namely the RPA or Landau damp-ing, the spreading width caused by more complexlplh®phonon configurations and the escape widthdue to the inclusion of the single-particlecontinuum. The known parameters of the Landau-Migdal effective interaction have been used in theapproach.At the giant resonance conference (May,1998) the au-thors of Ref. [1] announced that they extended theobserved energy interval up to 35 MeV in several ofthe A<90 nuclei including "Ni and found an addi-tional IS EO strength in the (25-35) MeV interval[5] . Thus, due to this fact and also with taking intoaccount a continuum under the monopole peak, 75-100% of the EWSR might be present below 35 MeVexcitation energy for 58Ni [6] . Our calculations give89.6% in this interval [7] . We have also shown [7]that a fraction of the IS E0 strength in 58Ni mightbe hidden in the experimental Background.
Just very recently the results of these measurementshave finnaly been analyzed in Ref . [8] . fiere the au-thors represented their results in the (12 .0-31 .1) MeVexcitation region. Thus we are now able to comparetheir results with our calculations in more detail andperform an analysis of the new experimental data.As compared with the analysis in Ref. [1], there aretwo new ingredients in Ref. [8] : 1)a nuclear reactiondescription is used following the method of Ref. [3],2)the giant resonance peak obtained after subtrac-tion of the continuum (see the experimental curvein Fig .2) is divided into 15 energy intervals varyingfrom 1-3 MeV each of which was analysed separately(in our calculations [2, 4, 7] 5 MeV bins have beenused).In Fig .1 we show the comparison of our calculations
with the newest experimental results given in Ref. [8]for the IS EO and E2 strength distributions . For theobserved energy interval we obtain the IS EO reso-nance mean energy value equal to 19 .9 MeV (definedas ml /mo) and 81.5% of the EWSR . The experi-mental data are (20 .03tCi) MeV and (7421 0 )%, re-spectively. For the (12 .0-25 .0) MeV interval, whichhas been analyzed previously [1], the new value of(58±6)% of the EWSR [8] is obtained which is nowmuch closer to our prediction of 71 .4% [2, 4] . Thus,there is a good agreement of the IS E0 resonancewith both the integral characteristics and the curveobserved in the experiment.
However, as one can see from the lower part of Fig .l,for the IS E2 strength we have not obtained a rea-sonable agreement with the present experiment . OurE2 resonance mean energy value and the depletionof the IS E2 EWSR defined in the (10 .0-20 .0) energyinterval are 19 .1 MeV and 47% while the experimentgives 16.1 MeV and (115±l5)%, respectively.
Fig.1 Distribution of the IS E0 and E2 strengths in"Ni . The experimental data are taken from Ref . [8].
10
6
5
45
133
Fig.2 shown the comparison of the inelastic a spectra.As in Refs .[8] the contribution of the IS EO, El, E2,E3; E4 and IV El resonances, which are calculatedmicroscopically, are summed to obtain the total crosssection. For the total cross section we obtain goodagreement between the new experiment and our the-oretical treatment, which causes some questions onthe analysis of Ref.[8].
8
8 8 1 8
8 e 1
8 8 1 8 8
1 '8 8 8 8 1
8
ti
5 10 15 20 25 30 5Ex (MeV)
Fig.2 Cross sections of "Ni(a, a» at Ec, = 240MeV and 9 = 1 .08' . The experimental data (solidline) and the background were taken from Ref. [8].The solid curve with dots gives the calculated total(summed) cross sections . In the Iow Part of the pic-ture the components of the total cross sections areshown without the background . In particular, thedotted line gives the IS EO contribution.
Thus, one can conclude that the new experimentaldata for the IS EO resonance in "Ni are in goodagreement with the microscopic calenlatitans whichdo not contain any fitting parameters . The val-ues of integral characteristics correspond now to theknown experimental systematics . In particular, aswas noted in Ref.[8], the EO strength located in "Niis consistent with recent results for "Ca, 28Si and24 Mg . In this sense the data about the IS EO res-onance in "Ni are final . All these results allow forthe hope that the problem of the IS EO resonance innuclei with A<90 [9] has been solved.
However, the disagreement between our analysis andthat of Ref .[8] for the IS E2 resonance only confirmsour earlier conclusion [2, 4, 7] about the necessity ofusing microscopic transition densities in the experi-mental analysis . Moreover, for the IS El resonancewe have not obtained an agreement with Ref .[8] Bi-
ther . The authors obtained only 41% of the IS EIEWSR and this strength was spread "more or less"uniformly from 12 MeV to 35 MeV . Our distribution
of this strength is shown in Fig .3. One can see thatthese is no uniform distribution . We obtained 89%of the IS El EWSR in the interval under considera-tion, and the mean energy value of 25 .0 MeV. Thesefigures are consistent with the results [10] for othernuclei .
5
15
25
35 45Ex (MeV)
Fig .3 Distribution of the IS El strength in "Ni (the-ory).
References:
D .H. Youngblood,
Clark, and Y .-W. Lui,Phys . Rev. Lette 76, 1426 (1996).S . Kamerdzhiev, J . Speth, G . Tertychny, IKPAnnual Report 1996, p .201G .R. Satchler and Dao T . Khoa, Phys. Rev. C55, 285 (1997).S. Kamerdzhiev, J . Speth, and G . Tertychny, inProceedings of the Intern . Conference on NuclearStructure and Related Topics, edited by S.N.Ershov, R.V. Jolos and V .V. Voronov, Dubna,September 1997, p . 347;in Proceedings of the Workshop on the Structureof Mesons, Baryons and Nuclei, Cracow, May1998, edited by S . Droidi and S . Krewald, ActaPhys .Pol .B 29, 2231 (1998).Y.-W. Lui, D .H. Youngblood, and H.L . Clark,Contribution to the Topical Conference on GiantResonances, Italy, Varenna, May 1998.A.van der Woude, Nucl . Phys. A649, 97c (1999).S.Kamerdzhiev, J . Speth, G . Tertychny, andF.Osterfeld, IKP Annual Report 1998, p .129Y.-W. Lui, H .L . Clark and D .H. Youngblood,Submitted to Phys .Rev . CA. van der Woude, in Electric and Magnetic
Resonances in Nuclei, edited by J . Speth(World Scientific, Singapore, 1991), p . 99.
[10] H .L . Clark, Y .-W . Lui, D.H. Youngblood et al.Nuel . Phys. A649, 57c (1999).
*The Institute of Physics and Power Engineering,249020 Obninsk, Russia.
70
58-Ni(a,a» Ea=240MeV
»: 1 .08deg
Ad, E2
w Rest (EL)Total+Backgr.
- Ltd et al. (1999)Background
4-4
60EI-IS
[5 ]
[6]
[7 ]
[8 ]
[9]
134
On the Interrelation Between Fermionic and Hasenk Excitations in Nuclei.
V. Klemt
Typical nuclear-structure calentations are problemrid-den in a twofold way already at the HF-RPA level.
First, it is well known for a Jong time that the barenucleon-nucleon interaction, due to its hard-core, doesnot produce realistic HF solutions . Yet textbooks andreview müdes frequently discuss this problem only in-cidentally, discussing RPA as if it would be performedwith a bare interaction.
A somewhat different, yet no less serious, problem isconnected with the correlations of the RPA groundstate, which is known to overestimate its real value(in the 6r-Mt of second order perturbation theory) bya factor of 2 [1].
Both of these fundamental problems can be handledmach more satisfactorily within the theory of finiteFermi systems, also known as Landau-Migdal Theory[2] . First, a universal effective interaction is intro-duced from the beginning, which can be assumed tohave the smoothness properties to make it suitable forHartree-Fock calenlotions.
Concerning the second problem, however, the originaltheory has to be generalized substantially [3] . Themain point is that even- and odd-particle systemshave to be treated as fundamentally inerrelated . Thiscan be achieved by describing the energy spectra ofeven-odd nuclei as formally resulting from the linear-response to the Hamiltonian [3],
where the T matrix is defined as the bound part ofthe two-body Green function (see Fig . 1).
XG44«9 )G3'3
Fig. 1
The new fundamental interaction amplitude K thenresults from the expansion of the T matrix into allthree directions simultaneously (see Fig . 2).
The horizontal (direct) particle-hole channel turns outto give the mean (HF) field (in terms of K), whilethe cross channels are responsible for the ground-statecorrelations, correct to second order in K.
lt remains to be examined whether more involvedmethods using the direct channel only [4] can tacklethis problem adequately.
Fig . 2
In addition it turns out that already the first (Tamm-Dancoff) part of the response function (see the follow-ing formula) gives the relevant contributions.
R1P34 ( ü)) E f -2--dn f 2a.Rlz34( s1 9' , = >o
(Ehla3al lep,)(digja 4 a31dio
(e0 1a 4a t3 1ep)(e i, ia t2 a l leo)w-Et,+is
[1] A. Klein, N. R. Walen G . Do Dang, Nucl . Phys.A535 (1991) 1
[2]A. B. Migdal, Theory of Finite Fermi Systems, In-terscience Publ . 1967.
[3]V. Klemt, J . Phys. G 8 (1982) 1547[4] S. DroidZ, S . Nishizaki, J . Speth,
Warnbach,Physics Reports 197 (1990) 1.
135
Review of Mechanisms for Direc.t. Breakup Reactions
G . Baur,S .Typel*,H .H .Wolter*,K .Hencken ,and D .Trautmann**
This work is published in Ref.[1]We review some simple mechanisms of breakup in nu-clear reactions . We mention the spectator breakup,which is described in the post-form DWBA . The rela-tion to other formulations is also indicated . An espe-cially important mechanism is Coulomb dissociation,lt is a distinct advantage that the perturbation dueto the electric field of the nucleus is exactly known.Therefore firm conclusions can be drawn from suchmeasurements . Some new applications of Coulombdissociation for nuclear astrophysics are discussed.In general, the dynamics of nuclear breakup reac-tions can be quite complicated . We wish to dis-cuss in this minireview style some limiting cases,which show some simple features . One may regardthe work of Oppenheimer and Phillips in 1935 [2, 3]as a starting point of the present subject . They triedto explain the preponderance of (d,p)-reactions over(d,n)-reactions by a virtual breakup of the deuteronin the Coulomb field of the nucleus before the ac-tual nuclear interaction takes place . Because of theCoulomb repulsion of the proton this would explainthe dominance of (d,p)-reactions . In this context,Oppenheimer [2] also treated the real breakup of thedeuteron in the Coulomb field of a nucleus . In themeantime, the subject has developed quite a Iot . Inaddition to the deuteron, many different kinds of pro-jectiles (ranging from light to heavy Ions, includingradioactive beams) have been used at incident en-ergies ranging from below the Coulomb barrier tomedium up to relativistic energies . At higher ener-gies, simplifications arise in the theoretical descrip-tion, since one can use Glauber theory (or the suddenapproximation in a semiclassical framework).In Chapter 2 we discuss the "spectator breakup"mechanism. The breakup occurs due to the stronginteraction of one of the constituents with the targetnucleus, while the "spectator" moves on essentiallyundisturbed . Since this subject has been dealt withextensively in the past [4], we wish to give a very briefoutline of the development over the last few decades,providing some of the relevant references . (This isof course a biased view of the present authors .) Wefind that the post-form DWBA is especially suitedto treat these processes . We discuss in Chapter 3Coulomb breakup using this post-form DWBA for-malism . This approach has beeen used for a lang timefor the breakup of the deuteron . Recently, this for-malism has also been applied to the breakup of otherhak nuclei with a simple structure, filze "Be . Also,using the adiabatic (in a sense to be explained below)approach, a formula reminiscent of the formula forthe post-form DWBA has recently been developed.The relation between the two formulations will bediscussed.In Chapter 4 we discuss Coulomb dissociation us-ing the semiclassical framework . First and higher
order electromagnetic effects are treated . "Post-acceleration" can be viewed as a higher order electro-magnetic effect . New possibilities for Coulomb disso-ciation experiments, also in the context of nuclearastrophysics are discussed in Ch . 5 . Conclusions andan outlook are given in Chapter 6.We discussed essentially two types of breakup mech-anisms. However, we saw that they are somehow re-lated, although more work should be still done toclarify this in more detail . The spectator mechanismis also useful as an indirect method to study astro-physically relevant reactions below the Coulomb bar-rier . This is much in the saure way as transfer re-actions have been traditionally used to study spec-troscopic factors . Peripheral collision of medium andhigh energy nuclei (stable or radioactive) passingeach other at distances beyond nuclear contact andthus dominated by electromagnetic interactions areimportant tools of nuclear physics research . The in-tense source of quasi-real (or equivalent) photons hasopened a wide horizon of related problems and newexperimental possibilities especially for the presentand forthcoming radioactive beam facilities to in-vestigate efficiently photo-interactions with nuclei(single- and multiphoton excitations and electromag-netic dissociation).References
G .Baur,S .Typel,H.H .Wolter,K .Hencken,andD.Trautmann, proceedings of the RCNP-TMUSYMPOSIUM on Spins in Nuclear and HadronicReactions , October 26-28 1999,to be publishedwith World Scientific Publishing Company,seealso nucl-th/0001045
J. R . Oppenheimer, Phys . Rev. 47, 845 (1935)
[3] J. R. Oppenheimer and M . Phillips, Phys . Rev.48, 500 (1935)
[4] G . Baur, F . Roesel, D . Trautmann and R.Shyam, Phys . Rep . 111, 333 (1984)
* Sektion Physik, Universität München, D-85748Garching, Germany**Institut für Theoretische Physik, UniversitätBasel,Klingelbergstraße 82, CH-4056 Basel, Switzerland
[1]
[2]
136
Influence of Damping on the Excitation of the Double Giant Resonance
G . Baur,C .A .Bertulani* and D .Dolci*
This work is published in Ref .[1]Double giant dipole resonances have been mainlystudied in heavy ion Coulomb excitation experimentsat high energies (for a recent review, see [2],see also[9]and [10]) . The feasibility of such experiments hasbeen predicted in 1986 [3, 4] where the magnitude ofthe cross sections for the excitation of the Double Gi-ant Dipole Resonance (DGDR) was calculated (seealso [5]) . The DGDR was observed at GSI[9] ;theseexperiments viere a first great success for the newaccelerators at GSJ[6]In ref . [4] a recipe was given for treating the effectof the width of the giant resonances on the excita-tion probabilities and cross sections . The dampingof the DGDR was studied in a microscopic approachby a group in the Ministry of Education , Scienceand Technology in Japan [7] In this paper we makea quantitative prediction of this effect using a real-istic coupled-channels calculation for the excitationamplitudes.We treat the excitation problem by the method ofAlder and Winther[8] . We solve a time-dependentSchrödinger equation for the intrinsic degrees offree-dom in which the time dependence arises from theprojectile-target motion, approximated by the classi-cal trajectory . For relativistic energies, a straight linetrajectory is a good approximation . We expand thewave function in the set kI ; k - 0,0, N} of eigen-states of the nuclear Hamiltonian, where 0 devotesthe ground state and N is the number of intrinsicexcited states included in the coupled-channels (CC)problem.We have obtained the dependence of the excita-tion amplitudes on the width of the giant resonancestates . We show that the effect reduces excitationprobabilities, and cross sections . We have developedan approach to solve this problem in realistic situa-tions . lt is demonstrated that the dynamical effect ofthe widths of the GR's in a time-dependent pictureleads to a decrease of the cross sections, more ac-centuated for Iow energy collisions . The energy frag-mentation of the giant resonances can be studied ina simple fashion within the harmonic model . The neteffect is also to decrease the cross sections with in-creasing width, specially at Iow energy collisions.AcknowledgmentsThis work was supported in part by the Brazil-ian funding agencies CNPq, FAPERJ, FUJB/UFRJ,and PRONEX, under contract 41,96 .0886 .00.Refererices:
[1] G .Baur,C.A .Bertulani and D .Dolci, Eur .Phys .JA,in print see also rruclsth/9905018
[2] C .A . Bertulani, J . Phys . G24 (1998) 1
[3] G . Baur and G .A. Bertulani, Phys. Jett . B174(1986) 23 ; G . Baur and U .A. Bertulani, Phys .
Rev . C34 (1986) 1654;
[4] C .A .Bertulani and G .Baur, Phys . Reports 163(1988) 299
P. Braun-Munzinger et al ., Proposal 814 submit-ted to the AGS Program Committee, SUNY atStony Brook, accepted 1985 (unpublished)
345
Paul Kienle Forschung im Focus, Edition Inter-from, Thesen und Texte
N .Dinh Dang, K .Tanabe, and A ArimaPhys .Rev C59(1999)3128
K . Alder and A . Winther, "Coulomb Excita-tion", New York, Academic Press, 1966.
[9] H. Emling, Prog . Part . Nucl . Phys. 3 (1994)
[10] G .Baur and C .A.Bertulani, "Proceedings of theInt . School of Heavy Ion Physics", Erice, Italy,October 1986, Plenum Press, ed . by P .A . Brogliaand G . F . Bertsch, p . 331.
* Instituto de Fisica,Universidade Federal do Rio deJaneiro 21945-970 Rio de Janeiro ,Brasil
[5]
[6]
[7]
{8 ]
137
138
6. ION SOURCES
BEA 1SPORT
SPECTROMETE
ARL
RADIATION PROTECTION
COOLER SYNCHROTRON COSY
142
COSY Machine Report 1999
U. Bechstedt, J . Dietrich, R . Gebel, K . Henn, A . Lehrach, B . Lorentz, R . Maier, D . Prasuhn, P . von Rossen,A. Schnase, H . Schneider, R . Stassen, H. Stockhorst, R . Töne
The year 1999 was predominantly determined by thedevelopment of polarized proton beams . The followingehallenging topics were treated in detail with majorpriority:
preparation of polarized protons beams up tomomentum 3 .3 GeV/cstochastic extraction of a polarized beamtransmission measurements and beam stackingstochastic coolingfast kicker beam extraction
Beam time statisticsThe scheduled beam time for COSY in the year 1999was 7536 hours . With an up-time of 7250 hours theCOSY complex features again a good reliability of 96%.About 75% of the scheduled time was available forexperiments.
polarized proton beamsDuring five weeks of beam time a concept has beendeveloped and realized to accelerate vertically polarizedprotons up to 3 .3 GeV/c . Using the existing verticalcorrecting dipoles the spin is flipped adiabatically at allfive imperfection resonances in the momentum range ofCOSY. The number of intrinsic resonances depends onthe supersymmetry P (number of identical unit cells).The largest supersymmetry P = 6 leads to only oneintrinsic resonance . However, the supersymmetry is lessthan 6 in general due to syrnrnetry-breaking installationsin the ring resulting in up to nine intrinsic resonances.To take this case into account the machirre was operatedwith a supersymmetry P = 2 . The high reliability of thetune jump system consisting of two pulsed air corequadrupoles allowed fast tune jumps that preserved thepolarization at all nine resonances. Tune changes of atmost 0 .06 within 10 ps are possible and double crossingof resonances is avoided by a fall time of 40 ms.Polarization and particle losses can be kept low duringacceleration if the beam Position is carefully aligned andthe vertical tune is fixed close to 3 .62 . The dynamic tunemeasurement allowed adjusting the tune duringacceleration as well as the time and amplitude of thetune jumps . On-line polarization measurements werecarried out during acceleration with the high precisiondetector EDDA. The polarized proton source currentlydelivers 5 yielding up to 109 polarized protons atmaximum energy. While the initial polarization level isabout 75% measurements reveai a significant and linearpolarization lass starting at about 2 GeV/c . This effecthas opened a lively discussion, which is still going on.
Stochastie extraction of a polarized beamA polarized proton beam at 800 MeV/c was fed to theTOF spectrometer with a spill length of 10s throughstochastic extraction . In this experiment an averagepolarization of 42% was determined, which is
significantly less than the measured polarization ofabout 70% before extraction . Investigations of the TOF-Collaboration show that the polarization level dropsapproximately Iinearly during extraction from about60% to 30% . Possibly this decrease can be assigned tothe stochastic extraction process in which the tunemoves slowly from below towards the extractionresonance (Q = 3 .666) thereby crossing several thirdorder depolarizing resonances . Their influence becomesmore harmful for Ionger spills . Further extraction studieswith different spill lengths are expected to give moreclarity on this polarization lass.
Transmission measurements and beam stackingTransmission studies from the ion source to the flat topintensity have been carried out with polarized andunpolarized protons to gain insight in cause and eure ofpartiele Iosses . lt turned out that only about 1% of thebeam out of the source is accelerated to flat top inCOSY, which is mainly due to the small cyclotronacceptance and the reduced beam quality after thecyclotron. To increase the intensity of the polarizedproton beam in COSY further stacking experiments withthe electron cooler at injection energy have been done.After about three minutes of stacking the flat topintensity of the beam was 4 . log unpolarized protons ascompared to log protons without stacking . Here, theintensity from the cyclotron was reduced to that of apolarized beam.
Stochastie coolingThe implementation of an optical notch filter forlongitudinal stochastic cooling has proven to be good.The notch depth could be increased by 10 dB whilesignal dispersion is drastically reduced as compared tothe old filier built out of solid air-filled coaxial Iines . Anenergy change can be handled within one hour withready-made optical fibers . First promising tests with acontinuously changeable optical signal path have beencarried out . This system comes into Operation in futureand will allow fast energy changes from cycle to cycle.
Fast kieker extractionIn 1999 the single turn extraction was studied with theaim to deliver 10 7 requested protons with a 1 ps pulselength to the Jessica experiment. To accomplish thisgoal the diagnostic kicker, which is normally used toexcite betatron oscillations, was fired fast enough so thatthe beam could be extracted within a single turn.Particle detection was carried out with the wall currentmonitor placed at the Iow energy target place . Asignificant intensity inerease was achieved when thetransverse and longitudinal beam emittances at injectionwere reduced with the electron cooler . Measurementssustain that the requirements of the Jessica experimentcould be fulfilied.
143
Polarized beam in COSYU.Bechstedt, J .Dietrich, R . Gebel, K . Henn, A .Lehrach, B . Lorentz, R. Maier, D . Prasuhn, P . von Rossen, A . Schnase,
H.Schneider, R . Stassen, H. Stockhorst, R . Toelle
During a very successful combined machine develop-ment and experimental beamtime, together with theEDDA collaboration, the conservation of polarizationup to the maximum momentum of 3 .4 GeV/c has beenachieved . On the one hand the EDDA experiment pro-vided an excellent polarimeter for the rapid analysis ofthe beam polarization, and on the other hand the im-provement in the preservation of polarized beam duringacceleration could directly be used by the experimentersin longtime runs for their physics experiment.
Dynamic tune measurement
An important tool used in the online analysis during thedevelopment of polarization conservation during ac-celeration was the system for the dynamic tune mea-surement system . The system, first introduced in 1998,has been developed further, such that an automizedmeasurement of the machine tune during acceleration ofthe stored beam is available online . 20 measurementswith a minimal separation of 30 ms are taken . The ad-justment of the start of the measurements in the msrange allows the online control of the tune change intro-duced by the fast quadrupoles, which are used to pre-serve the polarization during the crossing of intrinsicdepolarizing resonances (Fig . 1) . By averaging overseveral measurements it was possible to get a reason-able result with as Haie as 1E8 stored protons.
Fig . Vertical tune change by fast air quadrupoles asmeasured online by the dynamic tune measurement sys-tem.
Omiservatiirin of polarization during acceleration inCOSY
In the years prior to 1999 the emphasis of polarizedbeam development was the exploration of principles toaccelerate of polarized beam with negligible loss of po-larization . After developing the necessary tools duringthis time, the emphasis shifted during the two 1999beamtimes with polarized beam to incorporate thesetools into the routine Operation of the accelerator .
Polarized protons encounter two typen of depolarizingresonances during acceleration in COSY.
The first type are the imperfection resonances which oc-cur when the number of precessions per revolutionequals an integer .
y . Gn-k
Here y is the relativistic Lorentz factor, G = 1 .792846(anomalous magnetic moment of the proton), and k =integer . This type of resonance is caused by unavoid-able field and positioning errors in the magnet lattice ofthe ring . Lass of polarization at these resonances isavoided by artificialy increasing the resonance strength,such that the polarization direction is reversed whenprotons are accelerated across the resonance . If the reso-nance strength is sufficiently Zarge, the absolute value ofthe degree of polarization is preserved and a completereversal of the polarization achieved (spinflip) . At themomentum of the imperfection resonances the strengthof the resonance is artificially increased to achieve a to-tal polarization reversal when the beam is acceleratedacross . Vertical correction dipoles are used to increasethe average beam displacement (rms value) and the im-perfections will be enhanced . For the resonances y G=5and y G=6 the action of the vertical correction dipolesalso cause some loss in beam intensity which so farcould not be avoided without lass of polarization, and isthus tolerated.
The second type of depolarizing resonances are the so-called intrinsic resonances which occur when the condi-tion
y -G=k . Pis met . Here P = number of identical unit cells in thering (superperiodicity), , vy = vertical tune, k and y asabove . The strength of this type of resonance is in addi-tion to the errors in the magnetic lattice dependent onthe superperiod P of the ring . With increasing P thenumber of resonances decreases.The design superperiod of COSY(P=6) is broken byseveral installations in the ring (ANKE, e-cooler) . Formost cases only P=1 will be achievable such that allresonances shown in Fig . 2 have to be crossed duringacceleration of polarized beam in COSY.
In case of the intrinsic resonances a fast change in thevertical tune of the storage ring allows crossing of theresonance with minimal loss of polarization . For thispurpose, just before reaching the momentum of theresonance, fast quadrupole magnets are activated . Theycause a rapid change of the vertical tune with a risetimeof 10 ps (see Fig. 1), corresponding to approximately 10turns in COSY. Slower transition across the intrinsicresonances cause a loss in polarization . The falltime iswith approximately 40 ms Jong enough to avoid mul-tiple crossing of the resonance. The distance betweenthe resonances is dependent on the vertical tune of theaccelerator . Therefore the Jong falltime of the fast qua-drupoles requires a careful adjustment of the tune tohave enough time between neighboring resonances andto be able to fire the quadrupoles again, before reaching
144
the next resonance . With a tune of q 0,62 this hasbeen achieved. The manipulation of e beam to pre-serve the polarization of the protons is demonstrated inFig . 3, which shows printouts of online measurementsof vertical steerer and quadrupole currents in compari-son to the beam current measured with a beam currenttransformer.
Fig. 2 : Depolarizing resonances during acceleration ofprotons in COSY as a function of the vertical tune(working point). The line at qy = 0,62 shows the changein working point during acceleration of the beam . Allresonances are crossed during acceleration, for the in-trinsic resonances the action of the fast quadrupoles isindicated
The EDDA experiment, for which the reported polariza-tion development during 1999 was carried out, was ex-cellently suited to measure the beam polarization duringthe acceleration cycle . The asymrnetry of proton protonelastic scattering allows to deduce the degree of polar-ization of the circulating proton beam. The effectiveanalyzing power calibration needed for the caleulationof the polarization from the measured asymmetry is upto a momentum of approximately 1400 MeVie weil de-termined . For higher energies this calibration was pre-liminary, however, the data Laken in 1999 should allowto improve the calibration over the whole energy range.Fig. 4 shows a plot of measured polarization during theacceleration versus beam momentum . At imperfectionresonances the polarization is completely reversed(spinflip) . At intrinsic resonances the polarization is es-sentially preserved.
With the experience now gained in overcoming depolar-izing resonances, polarized bearns will become part ofthe routine operation of the accelerator .
Fig . 3 : a) Time dependence of beam intensity (BCT) andaction of the vertical correction dipoles . b) Timedepen-dence of beam intensity (BCT) and current through thefast quadrupole magnets. Timebase is 500 ms/div, Tmarkes the trigger time. The acceleration speed is 1 .15GeV/c/s.
Fig. 4 : Online analysis of the measured polarization inCOSY during acceleration . Above 1400 MeV/c the cali-bration of the analyzing power used in the analysis isstill preliminary. The sudden reduction of the polariza-tion at approximately 2630 MeVie is believed to be anartifact but needs to be investigated further.
Depolarizmg Resonaneessemi hold : intrinsic resonaneesbold :imperfeetion resonances
3600
3400
3200
-- , 0-Q
3000
2800 - --
2600 - --
2400
2200 1 +Q-
2000 , i
1800 ----, O+ t;
1400 Q. - -----
1000
800 --
600 : ----,-
4000,5
0,6
0,7
0,8
0,9
dir
1200
--- , :1+
, 6- Q---
-52 +
-n- -
-
n 9- Q
EDC A Pmlin( C gt(i( Itc
st.g2
a,.
REpC
0 1 500 1758 2000 2250 2500 2750 3000 3250P,,,n in 1vIeVIc
145
Determination of Partie 1
in COSY from the broad-band WM-
1. Mohos, J. Dietrich, J . Bojowald
al
For internal COSY-experiments measuring the energy-dependence of physical reactions during the accelerationramp a fast method of particle number determination isessential for the calibration of the reaetion results. The twomethods already used at COSY, e . partiele numberdetermination from the BCT-signal (beam currenttransformer) or from the narrowshand BPM-E-signal(s signal from
position monitor) [1], don't havethe needed aecuracy: the first one
of the offsetinstability of the BCT-signal ; the second one e of thedemanded duty cycle of buneh pulses of < 1 :3, which isnot fulfilled especially in the first pari of the achelerationramp. Therefore a method for particle determination fromthe average broad-band BPM--E-signal was developed toovercome such disadvantages . But this method alsopresupposes totally bunched current, . thecapacitive BPMs are not able to monitor the DC-part of thebeam.For the BPM-Ensignal us(t) and its average < us(t)>follows:
u,(t) = j Z B.,. - A . i B (t)
u.E (t)> . A . N e -
= 1 .25 . 10 -u N - A [Ni]
with i B(t)= bunch current, ZBpM=- 3 .443 [0] -transferimpedance, A=gain, N=part.-number, e=elementary Chargeand fre,=partiele revolution frequency. The gain A = Ao . Asin the BPM-electronics is composed of the fixed factor A0and the variable gain Ar in the Esehannel.The average signal <us(t)> can be measured in two ways:(1) In narrow-band mode the output signal is directlyproportional to the double value of the average Essignal,vvhen the narrow-band filtern (10 or 100 kHz) are set to thefundamental frequency, e. to the revolution frequency.This method is already used at COSY [2] . But due to thenonssufficient accuracy at duty cycles > 1 :3 a method wasdeveloped using the average broad-band Essignal.(2) Averaging the broad-band Essignal is exact regardlessof the duty cycle . For averaging two methods can be used:(a) Averaging by passive Integration . This method needs abaseline restauration after each bunch pulse to avoidbaseline shift due to the capacitive coupling in the main-amplifier . The COSY-BPM electronies contains a baselinerestorer (BLR) in the E-ehannel . But the aecuracy isdegraded at Iow particle nurnhers by amplifier r noise and atshort buneh distances . Therefore the following method wasapplied . (b) Determination of the average E-signal fromthe magnitude of the baseline shift, which corresponds tothe average signal amplitude.Fig . 1 shows the blockdiagram of the averagingeleetronies. By mearis of a fast sample&holdseircuit inseries with a capacitive coupling the instantaneous signalvalue in the middle between the bunehes is registered, e.the shifted live or the average value. By the su mgIow pass filter (LPF) the noise is reduced and a highaccuracy results, e. g . 10- 3 for 10 9 partieles per bunch and10 Hz LPF-hi dwidth. The phasessynchronized samplingsignal is derived from the broad-band E-signal itself and
Fig. 1 : Blockdiagram of the ave eng electronics
automatically tracks the revolution fitequelle . Theautornatic gain-control (AGC) amplifier stabilizes thesignal amplitude and ensures the correet Mnetimt of theei n& generator, even at large amplitude range. For theparticle number N follows with Ao=3 .3 in broad-bandmode and AB=10 as gain of the output buffer amplifier
N=2.4°10 '° < u« t» [v]A,
Fig . 2 shows the results of a measurement as an example.On top the BCT-signal raising up during accelerationproportional to ß . Theo. (curve 2) the average BPM-E-signal, which is proportional to the particle number andstays constant during acheleration with the exception ofsmall particle losses . Curve (3) shows the amplitude of
Fig. Measurement of bearn current (BCT) and average BPM-E-signal before arid during the
l .-
p . Time base is 0 .2 sIdiv.
the aceelerating rf-voltage . lt is elearly demonstratecl, thatthe average Essignal <ur(t)> ean reproduee the patticlenumber correctly only, when the
current is totallybunehed, e. if the rf-amplitude is high enough. Thepartiele number stored after acceleration results from theaverage BPM-E-signal to 2 .3 . 10 10. Partiele 1osses occurmainly before and at the beginning of the acceleration.
Refehenees[1] J . Biri et al ., WEB Trans. Nucl . Sei. 41 (1994) 221[2] J .Bojowald et al ., 1KP Annual Report 1997, p . 168
146
Preparation of High-Intensity Low-Emittanee Proton Beams by Electron Cooling in COSY
R. Maier, D. Prasuhn, H .J. Stein, I.D. Witt
Electron cooling ean be applied to increase the intensity ofthe COSY beam at injection . The standard procedure is to1111 die fing via stripping injection up to die full aperture . lfelectron cooling is active, the dimensions of the beamshrink so timt at a new injection the eireulafing cooled beamstays away from the stripper foil and, therefore, is notdestroyed. Cooling down the additional, high-emittancebeam onto the existing low-emittance coasting beam, theintensity is incr- , step by step during repeatedinjections . At low energies the intensity in a synchotron orstorage fing is restricted mainly by die space ehargeinduced incoherent time slüft known as Laslett tune shift[1] . An estnnate of düs space eharge fünft is given by thefollowing formula where we define the enüttances here andin die further text as
values of a tranverse Gaussiandistribution of the protons in the accelerator beam.
"v. = ( ß y / ro ) AQ 71 /2 [E (. .ry) +
Ey)"21 (1)
is die space charge limited number of protons in thering, /3 and y are the relativistic factors, r0 is die classicalproton radius (1 .5 x 10-18 m), AQ is the acceptable tuneslüft, ey and are the ernittances in the horizontal andvertical plane. e(x or y) equals to ey or ex whichever issmaller. Fig. 1 shows
for the COSY injection energyof 45 MeV versus die expression (e or y) + (ex s )"2) in adouble logarithmic plot. AQ is not a well-defined number,therefore, Nr,,2,x is represented by a band based on tune shiftsin the range 0 .025 5 AQ 5 0 .05 . In synchotrons whereacceleration follows directly after injection, AQ = 0 .25
1
10
100
1000(pm, 2cr errittanees )
Fig. Space Charge Iirnit of COSY at injection withmeasured emittances and beam intensities ofelectron cooled p beams. The points at 0 representthe beam directly after injection, points 1 and 2 arecooled beams after a single injection, points 3 and4 were obtained by stank cooling of multipleinjections.
is a commonly assumed value [1] . Cooling takes a fewseconds in which resonanees of higher order have thechance to causa beam losses . Therefore, a mich lawervalue for AQ is taken. The obtained ernittance is determinedby the balance of die cooling force of the electron coolerand heating forces, e.g ., sman angle Coulomb scattering inthe residual gas of die ring . Without stacking, under typicaloperating conditions (45 MeV p, 0 .2 A electron eurrent,10 -9 hP mean vaccuum pressure) we achieved 3 . . .9 x 109 p
in 2aemittances ex, of about 0.6, 1 .4 [im, respectively,see point 1 and point 2 in Fig . 1 . The enuttances of thecooled beam were detemined by the measured divergenceprofile of the neutral i . icles (hydrogen atoms originatingfrom recombination of protons and electron in the coolersection) at the end of the cooler telescope section and thecalculated beta ftmetions in die electron cooler section [2].
ud2 / ( fle.,c + 2 aec d + d 2 [ 1 + a ee 2]
)
(2)
ad is the width of the divergence profile, a and ß are theTwiss parameters at the position of the electron cooler, d(24 m) is the distance to die neutral particle detectorconsisting of two crossed multiwüe proportional countersfor the x and y plane. s is mainly dependent on the ß valuesbecause due to syrmnetry a values are below 0 .2 in ourcase . The beta values are around = 7, ßy = 20 m. Theproton beam intensity is measured by tlie beam currenttransformer unit (BCT) . The initial intensity of about3 . . .5 x 1010 representing the total filling of the fingacceptance of about = 60 and ey. = 24 Iim, see the pointsat 0 in Fig.l, is drastically reduced during the wofing timeof 5 . . .7 s . Nm. and emittance are dien the result of theexisting balance of cooling and heating forces . Thesomewhat higher intensity of point 2 is mainly due to moreprimary intensity from the cyclotron.
Stacking needs a careful control of the orbit in the vicinityof the stripping foil. The closed orbit bump must be farenough away from the feil so that the cooled beam does notpass through the foil but is dose enough to allow thecyclotron beam to be injected with suffiziently goodmatching. This is achieved by an appropriate beam steeringwith the injection bumpers . Applying a sequence ofinjections every 10 s, the cooled beam intensity has been
Time (10 s /ei)
Fig . 2 : Stacking of the p beam intensity in COSY byelectron cooling and repeated injections
147
increased up to 2 .5 x 1010, see point 3 in Mgl . From timeto time we observed rapid losses which we attribute tocoherent lass eff ects such as the resistive wall instabilitywhich becomes critical when the longitudinal Ap/p in thecooled beam is too small. The stochastie cooling system ofCOSY was used to apply RF noise longitudinally (and Iateralso transversely to enforce errintatlee growth) . The beamwas then stable revealing 2 .5 x 10 10 p in emittances of
ex = 1 .1 and sy = 1 .5 pm, Fig . 3 . Switching off the injectionwith the electron cooler still active caused a slowlydeereasing p beam intensity, Fig. 2, which stabilized at theIow level of a single injection. Fortunately, the decay timeis long enough to enable acceleration of the beam beforetoo much losses occur . Such a procedure may be used toaccumulate beam current when the primary intensitydelivered from the ion source is Iow as it is the case for theCOSY polarized source at present.
arbitrary units
Fig. Divergence profiles in both planes correspondingto 2rr enlittanees of 6,, = 1 .1 and ey = 1 .5 tm at2 .5 x 10 10 45 MeV protons in the ring.
A maximurn beam intensity obtained by stacking was4.0 x see point 4 in Fig. 1 . The Gaussian fits to thedivergence profiles reveal 2 dieminanees of 2 .7 and 3 .2 [un,Fig. 4. However, since the intensity gain was simplyachieved by increasing the frequency of the injections,Fig . 5, it is not clear whether the beam was completelycooled. The neutral particle detector is not sensitiveenough to show a possible uncooled halo An idea for
x planeGaussfit -2o- = 16 .0 rnm
10 20 30 40 50 60
10 20 30 40 50 60
Neutral pattlola divergence profiles (mm)
Fig .4 . Divergence profiles in both planes correspondingto 2cf ernittances of ex = 2.7 and ey = 3 .2 [Im at4 .0 x 1010 45 MeV protons in the fing . The cut inthe y profile is caused by the aperture of the exitwindows for die neutral partieles.
Future investigations is to apply much lower electron beamcurrents, e .g., 0 .05 A, first without stacking . Because theequilibrium ernittance after the fall cooling time of perhaps20 . . .30 s should then be higher, one might in a singleinjection step obtain the same cooled intensity as withrepeated injections . lf this should work, stacking c be
Time (25 s dies)
Fig .5 . Inereasing the p beam intensity by reducing thetime interval Ar between repeated injections.
applied in addition resulting in a perfectly cooled beamwith highest possible intensities . In practice, such injectionschemes could be applied in experiments with long cycleswhere the reduction of the cycle time is negligible.
A low-emittance high-current beam is mandatory for, e.g .,the ANKE storage cell target [3] . The target thickness/cm2in a storage cell is proportional to 12/d°, 1 the length, d thediameter of die cell . The beta functions at the foreseen siteof the ANKE storage eell are about 4 m . Assuming a400 mm long cell with a diameter of 15 mm, the acceptanceof the cell will be A ce n = 14 [im in both planes. To avoidhalo interactions with die wall of the cell, a beam emittaneeof a factor 8 smaller is usually required. In terms of 2o-emittances this yields about 1 lim . Taking our 2a valueof 3 p.m at injection after cooling and taking into accountthe adiabatic shrinking during acceleration as well asan 80% acceleration efficiency [2], we end up at with3 x 10 10 protons in e2 , < 1 p.m which could satisfy die basicluminosity requirements . Since die beam emittance beforecooling is much larger, it is advisable to consider a clarnp-shell mechanism which allows the cell to be opened forgetting through die fall beam intensity [3] . lt should benoted t h a t due to sman angle scattering in the target gas,cooling at the energy of die experiment is indispensable.The operating stochastic cooling system of COSY shouldbe able to compensate the beam heating by the target atleast up to 2 x 1010 protons [4].
References
W.T. Weng, Space Charge Effects - Tune Slnfts anResonanees, Physics of Particle Accelerators,Conference Proceedings, vol 1, New York (1987) 349
[2] H. J . Stein, R . Maier, S .A.
' D. Prasuhn, J.-D.Witt, Electron Cooling in COSY, Proc . 401 Workshopan Medium Energy Electron Cooling, Dubna 1998,Editor I . Meshkov, ISBN 5-85165-530-5 (1999) 258Kirsten Zapfe et ah, Detailed Studies of a High-Density Polarized Hydrogen Gas Target for StorageRings, Nucl . Instr. Meth . A 368 (1996) 293
[4] P. Moskal et a1 ., Determination of the COSY Proton F.
Beam Dimension by Means of the COSY-11Detection System, this Annual Report
0 20 30 40 50 60
10 20 30 40 50 60
Neutral partioie divergence profiles (mm)
2o
` 1"
t 5 s
t 3 s
a t 2,. Ld
2 : 2 6x10 103 .6x 10 10
4 .0x10 '0o
y planeGaussfit--20- .8 .0mm
arbitrary units3oo
200
100
200
100
[3]
148
Fast Kieker Extraction at COSY
J . Dietrich, J . Bojowald, H . Lawin, I . Mohos
In the cooler synchrotron COSY two kinds of beamextraction were foreseen and realized : resonant extractionand stochastic extraction . Now a fast beam extraction forthe new experiment JESSICA (Jülich ExperimentalSpallation Target Setup in COSY Area) [1] is of greatimportance for prototyping the high power target of theEuropean Spallation Source . For the experiments protonpulses with energy < 1 .5 GeV, pulse length of < lp.s andintensity of more than 10 7 protons per pulse are needed.The kicker magnet in the COSY ring, installed for beamdiagnostic measurements [2], is used for first experimentsof fast beam extraction . The procedure starts in the sauremanner as for resonant beam extraction for externalexperiments . A closed orbit bump in the horizontal plane islocated near the electrostatic septum. By means of thekicker magnet the beam bunch (width about 200 - 500 ns) isskort-time (width 0 .75 - 2 las, rise- and falltime < 200ns)deflected . The kicker excitation is synchronized withrespect to the COSY-rf signal and can be adjusted in timeby programmable delay, so a unique deflection of the totalbunch can be performed (bunch synehronous kick) . Therepetition rate of the kicker excitation is 1 Hz . The minimalCOSY cycle time varies from 2 s in the ease of Iow energyto 5 s in the case of the highest energy . For increasing theintensity of kicked beam a reduction of beam emittance isnecessary . In our case electron cooling for some seconds atinjection energy is used.For non-beam disturbing diagnostics of intensity and timestructure of the kicked and extracted beam the wall currentmonitor (WCM), which was formerly located in the ring,was installed in the experimental area of JESSICA . TheWCM is a broadband pick-up (100 kHz - 200 MHz) fordetailed measurements of beam pulse intensity and shape.First experiments at 180 MeV showed a pulse of theextracted proton beam with width (FWUNI) of some 100 nsand intensity of 110 7 protons . As evidence for the fastbeam extraction fig. 1 shows the WCM-signal and thesignal from a scintillator in the extraction beamline, buttaken out of beam. Furthermore are displayed the kickersignal and the E-signal of a beam position monitor (BPM)in the ring . The latter one clearly shows the sudden decreaseof the internal beam caused by the fast extraction . Fig . 2demonstrates the importance of beam cooling for theeffective fast heam extraction.In the next time the fast kicker process must be investigatedin the whole energy range of COSY and the process raust beoptimized to enhance the intensity of the kicked protonpulse.
References[1] W.Breuer et al ., IKP Annual Report 1998, Report Jül-3640 (1998)180[2] J .Bojowald et al a IKP Annual Report 1990, ReportJül-2 4 62 (1990)184[3] H.Lawin et a1 ., IKP Annual Report 1991, Report Jül-2590 (1991)236
Fig . 1 : Fast kicker extraction at 600 MeV/c . For details see thetext. The time differences between the signals are due to differentparticle travelling times and non-calibrated cable lengths.
Fig. 2 : Fast kicker extraction with (upper) and without (lower)electron cooling at injection energy and following acceleration to180 MeV . For the time difference between the signals see fig . 1.
149
Preparing a Broadband Cavity for 1
at COSY
A. Schnase, M . Böhnke, FA . Etzkorn, U . Rindfleisch, H . Stockhorst
AbstractA structure based an the material VitroPerm [1] is proposedthat allows the simultaneous application of a fundamentalfrequency and higher harmonies . The frequency range ofthe fundamental covers the operation range of COSYincluding the Option to work with deuterons : 400 kHz to 1 .6MHz. No tuning loop is necessary . Even lower frequenciesare possible - limited by the solid state power amplifierswhich operate at a minimum frequency of 300 kHz.
Description of the cavityExperiments with small samples of VitroPerm cores [2], [3]have shown that such a material is a good candidate for acavity . The scaled results led to the mechanical dimensionsof a real cavity, which consists of two halves filled with 6VitroPerm cores for each side . The Iayout is shown in fig . 1.
Fig . 1 : Layout of the final cavity structure
The dimensions of one core 200 mm inner diameter, 400mm outer diameter, and a thickness of 25 mm are Chosen tominimise the cavity size and the amount of magneticmaterial that is necessary to reach the desired impedance.The inductance of one core is proportional to the logarithmof the outer radius ra, where the volume of the material is
V = 2-rc. h . (ra2 ri2).
If the magnetic coupling between the cores can beneglected, e .g . there is enough distance between the cores,the resulting impedance of a group of cores is comparableto the sum of the impedance of single cores . The impedanceof a single core is shown in figure 2 .
The impedance properties of the cores as a function offrequency f (in MHz) can be described with formulae like:
Z = a . fb with the parameters a and b.
Zreal = 75 ,Q-f034Zimag -= 45 nf0.27
This implies that the phase of the impedance is almostindependent of the frequency.
When this material is placed inside a water bath the cavityimpedance is also a function of the capacity of the waterwhich has a dielectric constant
80 . The conductivity of
the water plays an important role, too . Figure 3 comparesthe impedance of one cavity half filled with air and filledwith tap water . The broad-band behaviour is related to theIow resistivity of the tap-water.
Fig . 3 : Impedance of a half cavity filled with air or tapwater
In comparison to the air-filled case the impedance decreasesonly slightly if the material is cooled with the low-conductivity water of COSY (fig . 4) . These measurementsare in good agreement with those performed at KEK [5].
0
1000 2000 3000 4000 5000 6000 7000 8000
frequency [kHz]
Fig. 4 : Impedance of a half cavity filled with Iowconductivity water
impedance[Ohm]
MIMIIIMMIIIMM
1 IM111UM1311116 m...pM::fä111111EWIEMP0MällOMM11111M1MiiI1IMM1111Z1I1E3IM
UriaMORIMM- Mill111INIE»1111111111M1M1IIMMMIMWIMMEMUMMMIMM111111M1IMMIIIIIIII1M1I3
4000
frequency [kHz]
Fig . 2 : Impedance of a single core (single turn winding)
.."pommmm. 1.1111.j1111111111ä ,änffl:H:!i.
. .
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The cavity will be connected to the amplifier by two specialcoaxial transmission lines where the outer dimension (app.100 mm) is comparable to a 4 1/2-inch transmission systemSMS [4] . The inner diameter is about 4 mm whichcorresponds to an impedance of about 190 ohms.Installation constraints exclude the betten solution to placethe amplifier as close as possible to the cavity . Availablespace is 1irnited and experiments with the amplifier shouldbe possible without interrupting the operation of COSY.The same amplifier formerly connected to the VitroVaccavity will be used . The necessary modifications result froman intense information exchange with colleagues at KEK[6].The transmission lines are about 7 m long each . Theirinfluence on the impedance has to be taken into account fora real operation of the cavity as is demonstrated in figure 5.
0
1000 2000 3000 4000 5000 6000 7000 8000frequency [kHz)
Fig . 5 : Impedance of one cavity half with 7 m transmissionline seen by the amplifier
The material is placed inside a water bath . Therefore awaterproof coating is mandatory . The first coating revealedproblems. There was corrosion at places where the coatingwas not perfect . To prevent a contamination of the maincooling loop, a separate circuit will be bunt and a heatexchanger for 50 kW heat will be added . Also, tests to usethe cooling medium Fluorinert FC-77 will be carried out.
Signal generationA digital synthesizer [7] generates the fundamental togetherwith 2 higher harmonics . The second, and either the third orthe fourth harmanie can be applied . The Signal levels of theharmonics are chosen to generate the desired waveform.The synthesis of the higher harrnonics will be integratedinto the COSY control system . Seven DSP functiongenerators control the frequency of the fundamental, and thereal and imaginary part of the three combined sinusoidalfourier components . A user interface in TCL/TK, shown infig . 6 gives access to the hardware . lt talks via TCP/IP to aV14E-contoner, running with OS-9 and bunt like the onesin the noise extraeton systems (USE) . These controllerswill be replaced by Celeron based VME-boards operatingunder LINUX to increase performance in the near future .
T
h=1
.08 MpüUido (8.-10)
EM Pdmä 11
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,
otq ,, 8831
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Anm . 2 (0.-63)48 010en34y 8tMdby 044+ RF- 0E8
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Fig . 6 : User interface in TCL/TK.
OutlookThe acceleration voltage requirements of COSY allow beamtests with this cavity by semiconductor amplifiers in the kWpower range . The next step is an upgrade to a tube amplifierwith 50 kW RF power.
References[1]Vaccumschmelze Hanau GmbH: "Kerne und Bau-
elemente", Datenbuch 1998
[2]M. Böhnke, F.si . Etzkorn, R . Maier, U. Rindfleisch, A.Schnase, H . Stockhorst: "Broadband SynchrotronCavity for COSY with Minimum Size based onVitroPerm", PAC99, New York, p . 851
[3] M. Böhnke, F . st . Etzkorn, U . Rindfleisch, A. Schnase,H. Stockhorst : "Broadband Cavity with the Nanocrystalline material VitroPerm", IKP Annual Report 1998
[4] Produkthandbuch Koaxiale Leitungen, Spinner GmbH,München
[5] C. Ohmori, E . Ezura, M. Fujieda, Y. Mori, R.Muramatsu, H . Nakayama, Y . Sato, A. Takagi, M.Toda, T . Uesugi, M. Yamamoto, M . Yoshii, KEK;M. Kanazawa and K. Noda, NIRS : "High Field-Gradient Cavities Loaded With Magnete Alloys forSynchrotrons", PAC99, New York, p . 413
[6] Y. Sato, M. Fujieda, Y. Mori, H. Nakayama, C.Ohmori, R . Muramatsu, T . Uesugi, M. Yamamoto, M.Toda, A . Takagi, M. Yoshi, KEK; Y. Taniguchi,Denki Kogyo Co . ; K.'OHTA, Ohta Electronics Co .:"Wide-Band push-Pull amplifier for high gradientcavity", PAC99, New York, 1999, p .1007
[7] F. J. Etzkorn, S . Papureanu, A . Schnase, H.Stockhorst : "Towards a cavity for higher har-monics", IKP Annual Report 1994, p . 221ff
ET C inne
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151
Magnets, Alignment and New Installations
U. Bechstedt, L. Conin, G. Dolfus, R . Enge, P . Faber, K . Jach, G. Krol, G . Langenberg, M . Müskes t , H . Pütz,B . Rogozik, D . Ruhrig, T . Sagefka, F .Scheiba
The year 1999 was filled with a lot of different activities.Driven by measured tune variations during the accelerationramp of the COSY machine we did a carefulremeasurement of an arc type quadrupole magnet.Measurements were done starting with excitation currentsas low as 5 A in contrast to the series measurements of allthe quadrupoles that started at excitation currents of 50 A.We found that below 40 - 50 A the remnant Field of thefron is not negligible . The deviation from a linearbehaviour at 15 A is approximately 2% . Because of thescaling of the excitation currents of the magnets with themomentum during acceleration this leads to an error in thefunction for the quadrupole currents . Up to now this iscompensated by the unphysical large values for the timeconstants of eddy currents introduced for the arcquadrupoles.Another magnetic measurement activity at the end of theyear was to assist the colleagues of ISI in the measurementof the permanent magnet configuration of a sputterapparatus . Results of the measurements allowed to shimthe magnet configuration to achieve a better performance.A lot of work of the whole group during the year wasrelated to the set-up of a second polarised ion source . Thissource shall be used to Lest further improvements of theoperational source . As well it shall be used as a spare forthe operational source during polarised beamtimes.The storage cell at the atomic beam target of the EDDAexperiment[1] was reinstalled with a slightly changedconfiguration of the bellow . lt turned out that there was aproblem with the alignment of the copper cold fingerwhich had to be solved by a remachining of the cold headof the He cooling stage .
The wall current monitor that was taken out of the COSYring and replaced by a beam profile measurement devicetwo years ago was installed at the external low energymeasurement place . It was successfully tested to allow forthe measurement of --1µs particle pulses required by theJESSICA experiment.Two twofold scraping systems were built by the centralworkshop and successfully tested after some problemswith helicoflex vacuum seals . They were installed into thetarget telescope in front of and behind the EDDAexperiment . These scrapers will allow to reduce the haloboth horizontally and vertically for the ANKE experiment.The installation of an external polarimeter between thefirst two multiwire proportional chambers of the extractionbeamline was prepared . The polarimeter was built by theuniversity of Hamburg. It is a copy of the internalpolarimeter which allows to exchange the bothpolarimeters in case of a problem and to check forsystematic differences . The pneumatic vacuumfeedthroughs to move in the targets made of carbon andpolyethylene as well as the target material were ordered andelivered . The polarimeter will be installed in the firstshutdown of 2000 when the last missing vacuumcomponents to be supplied by the central workshop will beready.Besides these activities we did some planning work foradditional external measurement areas . As a first step theconcept of a new hall with three additional measurementareas was developed . In a next step the costs for a newbeamline to the Bast hall of the cyclotron building wasestimated.
References:
[1]
Magnets, Alignment and New Installations, U.Bechstedt et al ., IKP Annual Report 1998, p . 155
Died in July
152
The COSY Electrical Emergency SystemH. Borsch
Due to the use of very high currents andlor voltages anaccelerator environment posen a considerable risk forpeople working therein . lt is mandatory in such a situationto provide a system that allows a quick reaction to suchemergencies . Therefore, parallel to the construction ofCOSY, a concept for an Electrical Emergency System(EES) had been laid out to remove eleetrical power to theentire accelerator system in case of acute danger. Over 100push buttons have been distributed all over the acceleratorbuildings to guarantee a nearly instant removal of the 10kV respectively 21 kV primary power to the powertransformers . Only a limited number of systems vital for anorderly restart and possessing inherent safety, like lights,computers, vacuum systems, cooling components, andelectronic racks are exempt from this emergency power-offsystem.
In the floor plan of the facility in Fig . 1 the diversepositions of those emergency buttons are shown . The EES(NOT-AUS Anlage, in German) is divided into twosubsystems . The first encompasses the relay circuits whichinitiate the removal of primary power . Only relays, thathave been certified for this special purpose, are usedthroughout in this section . For two selected power supplies(the large dipole power converter and fast kicker-system) aleading contact is provided that enables the removal of theprimary power without possibly damaging the these powerconverters.
The second system serves for surveillance and displayingthe status of the FES . A memory programrnable controller(Simatic S5-IOOU) polls
permanently the status of each emergency button anddisplays it an a screen . This allows to directly pinpoint thebutton which has triggered the emergency power down ofthe accelerator and helps to guide rescuers to the scene . Inaddition, the public address system Info rms peopleimmediately of the emergency power-off situation.
There is one important pit fall to watch out when handlingsignals of those emergency buttons . In a facility the size ofCOSY the cable length involved can reach up to 1200 m.In this case the current flowing via parasitic capacitancecan reach values that exceed the hold current of a relaypreventing thus the intended function . This danger hasalready to be taken into account when the cable lengthexceeds 500 m. In our case, parallel resistors to the relaycoils ensure the correct function of those emergencyMuttons.
The EES has been in operation since fall 1992 . Theexternal experimental area BIG KARL was added in April1993 and the TOF (Time Of Flight spectrometer) site wasadded in March 1994 . One month later the external area forexperiments with proton beams up to 200 MeV calledNEMP was added to the system. Fortunately, no realemergency has forced anybody to make use of this systemup to now. But there were some unintentional emergencyshut downs due to confusing the buttons with some otherfunction or inadvertently pushing a button while handlingconstruction material . Still, we judge the present system asa good compromise that is leaning toward safety.
Fig . 1 : COSY floor plandepicting the position ofthe emergency buttons
153
154
D B MA6. ION SOURCESTRANSPORT
156
Ion Sourees at COSY
B . Dahmen, W. Derissen, R . Enge, H .P . Faber, O. Felden, N . Gad, R. Gebel, M . Glende, H . Hadamek, A . Müller,U. Rindfleisch, P . von Rossen, N . Rotert, Th . Sagefka, H . SingerJ . Bisplinghoffl , P .D . Eversheim l , D . Rosendaal '
Ion source operationThe two unpolarized H- ion sources [1] operated reliablyfor a total of 7061 hours in 1999. Polarized beams wereused in two beam times . In early 1999 a polarized beamwas extracted from COSY with a momentum of 800 MeV/c
Date
Fig. 1 : Daily samples of polarized beam current measure-ment at the first cup in the source beam line.
for the proton proton bremstrahlung experiment at the timeof flight spectrometer TOF. In a combined machine devel-opment/ EDDA run first spin correlation coefficient datawere taken at two beam momenta . In addition polarizationconservation in the synchrotron up to the maximum beammomentani of 3 .3 GeV/c was further optimized [3] . Thepolarized ion source was available for 72 % of the sched-uled 31 days beam time. Down time was caused by therecovery operation after a research center power failure andto refill/ replace source components.
Design refinernents of the polarized ion sourceAll original parts in the cesium beam section (fig . 2) werereplaced by improved components. A second cesium ion-izer was set in operation with a superior setup of the ex-traction system. The new parts have been optimized inaccordance with the operational experience . The perform-ance of the neutralizer has been advanced . The magneticdesign of the neutralizer flapper valve and its bearings has
been improved . The minimum attainable valve open periodwas cut in half. The operation temperature of the cesiumreservoir could be decreased from 310°C to 270°C.Thereby reducing the loss of cesium and the contaminationof the nearby sections . A new deflector chamber was set inoperation for the Jong EDDA run in November. Ist de-creased deflection angle for Cs+ and the matched of thedeflector geometry reduced the deflection high voltage byalmost a factor three . This removed the former limitation ofthe maximum cesium beam momentum due to sparking ofthe cesium deflector . As a result the geometric emittance ofthe cesium beam has been reduced . The H- extraction anddeflection elements have been under detailed investigationan an external test bella to improve extraction efficiencyand beam quality.
Augmenting of beam diagnosties at the polt ized ion source
Fig . 3 : The improved profile scanner for the intensecesium beam . The wire is rotated clockwise from 0° to270° talcin g a vertical and a horizontal scan the beam.
The startup procedure of the cesium beam part (fig . 2) issimplified by new beam diagnostic elements.Four beam profile scanner modules (fig . 3) allow the onlinecontrol of the cesium beam envelopes . Figure 4 shows thehardcopy of the online oscilloscope display of horizontaland vertical profiles . Profiles taken at different positionsbehind the quadrupole triplet allow determining the emit-
Fig . Schematic view of the polarized ion source with the beam profile scannersystem and the calorimeter .
157
Atom icBeam
Source
ChargeExchange
Region
Defiector
CesiumChamber Neutraiizer
Ionlaer
and Cafortmeter
tance of the cesium beam. This provides the reliable Infor-mation to decide the replacement of the thermal ionizermodule . Data taken with this system was also used to de-
Fig . 4 : Online optimized profiles of the cesium ion beam atthe position of the neutralizer . The distance per division is11 mm.
termine the pararneters of the quadrupole system and tooptimize the geometry of the cesium beam line for hightransmission. A typical structure of the Cs + beam calculatedwith TRANSPORT is depicted in fig . 5.A set of correcting dipoles has been added to the magneticquadrupole triplet to remove beam displacements in the
Fig . 5 : Cesium beam envelopes for the optimized distancebetween the ionizer and the First quadrupole . (1 m/div inbeam direction and 10 rmnldiv transversal)
charge exchange region . A compact calorimeter has beeninstalled between the charge exchange region and theatomic beam source . The calorimeter consists of a cylindermade of copper, thermally isolated on a linear support.Exposing the
cylinder for a fixed time period to the
Fig . Cesium sputter mark on the calorimeter (left) and animage of the atomic beam at the entrance of the chargeexchange region (right) .
cesium beam the energy deposited rises the temperature andis a measure for the cesium intensity . By means of oneprofile scanner and a faraday cup the calorimeter elementthe calorimeter was calibrated . Fig . 6 shows the calorimeterafter calibration . The circular mark of - 9 mm diameter fitsto the measured beam profiles . The weak sputter marks atthe top occurred while moving the calorimeter in and out ofthe cesium beam.The position and the diameter of the ground state atomicbeam was roughly checked by reduction of a red copperoxide produced by heating a copper foil to 170°C . Theposition and the diameter meet the expectation . The meas-urement took about 12 hours with an increased repetitionrate of the pulsed atomic beam source.
Fig.7 : Measured fluctuation of the permeability of 15 po-rous tungsten ionizer buttons under standardized condi-tions . The symbols under the x-axis identify manufacturerand enurnerate the buttons.
Production of tungsten surface ionizer buttonsThe high demand on the uniform quality of the tungstenbuttons led to improved manufacturing and cleaning proc-esses . Figure 7 shows the obtained progress in quality . Thebuttons P5 to 34 show a large variance obvious in theirconductance, which hints at their performance . The buttonsfrom the latest charge, J5 to 39, were particularly treated toexclude contamination of essential surfaces . This uniformbehavior was also confirmed in ionizer operation.
Test bench for ion source componentsTo remove the constraints given at the polarized source themain components have been set up on an independent tsatbench . In collaboration with the ISKP of the universityBonn essential parts of the polarized ion source were dupli-cated and improved to be used at this test bench.
1 Institut für Strahlen und Kernphysik, Universität Bonn
[1]H. Beuscher et al ., IKP Annual Report (1996)[2]P.D . Eversheim et al., IKP Annual Report (1996)[3]R. Gebet et al ., IKP Annual Report (1998)[4]P.v. Rossen et al ., IKP Annual Report (1998)
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160
Magnetic Spectrograph BIG KARL
J . Engel, W. Derissen, R . Jahn, K. Kruck, H . Machner, R. Maier, P . v . Rossen, R . Töne,GEM- and MOMO-Collaboration
The collaborations of GEM and MOMO were the mainusers of the high resolution spectrograph BIG KARL . TheMOMO group continued its investigation of two K-mesonproduction in the reaction p d -3 3 He K±K- close tothreshold at two new energies being 40 and 56 MeV abovethreshold . Extracted beam intensities from COSY had beensufficiently high, delivering 10 9 protons per second in a 12s beam spill . Additionally, the beam halo which had been agreat concern in previous runs, and had prompted theinstallation of a particular veto counter, was well belowthe tolerable harnt and did not impair at all themeasurement.
The GEM collaboration performed its study of the
simultaneous measurement of the reactions p+d -~ it 3Hand p+d x° 3He with an improved set up. Thisexperiment measures 3He particles at the standard focalplane and 3H at the exit slit of the side yoke of the firstdipole magnet of the spectrograph . By this method iteliminates uncertainties originating from target thicknessand beam intensity normalization . The particleidentification at the exit of the first dipole had beendifficult in the past due to a high background rateproduced by the primary proton beam hitting fron Partsnearby . To counter this limitation a small angle beamswinger system had been placed in front of the target. ltallowed to change the angle of the COSY beam by ±23mrad, controlling in this way the position where theprimary beam hit the side yoke of the ferst dipole . Thismodification allowed to reduce the disturbing backgroundby more than one order of magnitude . Additional measureslike improving the directionality of the trigger hodoscopeand auxiliary veto scintillators reduced the trigger rate toacceptable levels . This enabled the group to clearly filterout the 3H events.
The magnet used to swing the beam had originally beenconceived as a fast switching magnet for the Cs +-beam ofthe polarized ion source. Its laminated design and themanufacturing were performed in our institute . Due to itsextremely compact size it was perfectly suited to fit intothe tight space in front of the scattering ehamber . Anisometric view of this device is depicted in fig . 1 . Besidesroutine maintenance of the large spectrometer twoproblems surfaced in etanneeton with the water cooling.The third of the entrance quadrupoles had developed pin-hole water leaks at two positions that were closed withrubber plugs side stepping thus the difficulties that wouldhave been connected with brazing those holes tight . In theother case the cooling system of a 200 kW powerconverter was involved . As more and more devices havebeen attached to the cooling system in the rezent past, asuccessive reduction of the water pressure difference hasoccurred . This finally prompted the failure of the power
Figure 1 : Isometrie view of the beam swinger magnet . Forclarity the middle Part of the laminated yoke is not shown
converter due to overtemperature . As a remedy the coolingcircuit of the power converter was split allowing now morewater to pass through the crideal transformer section whichhad caused the temperature failure.
161
162
1
Radration Protection
H.J . Probst, H . Schaal, Ch . Pohl, J . Göbbels, K . Klafft
The research efforts at the Iow energy measuring place(NEMP) were finished in 1999 . Now this experimental areashould be used for spallation experiments (JESSICA) with arnaximum proton energy of 2 .5 GeV and a maximum beamcurrent of 10 8 p/s . Because these parameters were muchmore stringent as before the radiation protection measureswere to deterrnine and (partly) to carry out.
For the shielding calculations we used the Monte Carlocodes HETC and MORSE of the Code System HE ES/11.The geometry of the target-moderator-reflector assembly ofJESSICA was modelled with the modifications that themercury target had a length of 65 cm only, the lead reflectorrods and their wohlig water forrned a homogeneous mixtu-re, and all moderators contained water . The computer si-mulations were performed for an impinging proton beam ofintensity 108 p/s and energy 2 .5 GeV. We scored the energydependent neutron fluxes crossing the surface of a segmen-ted sphere with radius R = 1 .8 m and its center in the mer-cury target . °s surface lies entirely inside the JESSICAarea. The scored energy and direction dependent neutron
fluxes were multiplied by the dose rate conversion factors/2/to get the dose rates D(R) . We found the maxirnum doserate value of 2 .5 mSv/h in the beam direction. For the otherdirections we used 2 mSv/h because die highest valuecaleulated was 1 .9 mSv/h.
The interesting dose rates D(x) at positions x outsidethe shielding walls of the JESSICA area were thencaIculated using the simple attenuation equationD(x)=D(R) (R2/x 2 ) exp(-d/X) with d the thickness ofthe shielding wall and X the attenuation length of highenergy neutrons . We used for the concrete shieldingwalls A.= 55 cm.
From the calmlations for all areas in the horizontal planeoutside die JESSICA area dose rates less than 3 .5 gSv/hwere found (see fig. 1) . lt should be mentioned that for thedose rate ealmlations of Position PI in the TOF area, wherethe shielding wall thickness is about 1 m only, die simpleattenuation calullatim had to be reset by a ealeulation usingenergy dependent attenuation lengthes.
TP2
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Figure 1 : Neutron dose rates in horizontal plane outside JESSICA area
165
The calculations for the areas above the JESSICA areashowed dose rates of about 500 ;.tSvlh for the firnt floor, ofabout 40 IitSvlh for the second floor, and of 7 .5 gSv/h forthe third floon
lt is evident that the dose rates in the First floor are to highfor a controlled area . Therefore, this area has to be treatedas a closed area. The areas of the second and third floor willbe further controlled areas . Besides, the rooms near theJESSICA area must be equipped with additional neutronmonitors, because they are accessible during JESSICAoperation . For, the assumptions and parameters used for theshielding calculations carraot be guaranted in any ease.
In order to use the JESSICA area with the new speeifiea-tions a licence by the appropriate authorities is needed.Because of the convincing results of the calculations and theoffered radiation protection measures the licence was givenin November 1999 without essential injunctions.
In 2000 a strongly modified radiation protection ordinancewill be ettomed. The consequences for the COSY operationand the handling with radioactive materials in the IKP werediscussed with the cornpetent authorities in October 1999 . Agratifying result was that it is not necessary to change theradiation protection areas (closed areas, controlled areas,supervised areas) inside and outside the IKP in spite of themore restrictive dose values of the new ordinance . An addi-tional demand of die new radiation protection ordinancesettles that the effective dose of the not occupationally ex-posed persons must not exceed the value of 1 mSv per yearduring stay in supervised areas . This value is not exceeded,too.
As verification the neutron doses for 1999 were determinedat the positions of the neutron monitors (totally 35 moni-tors) of die radiation surveillance system of COSY . Thefigure 2 shows the neutron doses for 1999 at the 35 measu-fing positions (labelled as ,,annual neutron dose") . The doseof the accompanying 'y-radiation in compaxison to the neu-tron dose was determined often in the gast years . The y-dosedoes not exceed 50% of die neutron dose . So, the total dose(neutron and y-dose) is less than 150% of die neutron dose.Because persons do not stay essentially longer than 2000hours per year in the FZJ the total exposure for persons inthe supervised areas of COSY is less than 35% of the neu-tron dose . The figure 2 shows this total exposure labelled as,,max. annual total exposure" . As you can see no value ofthe annual exposure exceeds 1 mSv.
References
/1/ P . Cloth et al ., HE ES A Monte Carlo Program Sy-stem for Be -Materials Interaction Studies, KFA-Report Jül-2203 (1988)
/2/ B . Wolfertz, Entwicklung eines ingenieurmäßigen Si-mulationssystems zur Berechnung von Strahlenschutz-parametem an Protonenbeschleunigern im Energiebe-reich bis 3 GeV, KFA-Report Jüls3197 (1996)
annual neutron dose
max . annual total exposure
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0
01 WAZ NM4 NI«
NMIO !NMI2 M94 41tt -_ 8 n,2n ' 1 ,22 IN,24 1NM26 14°0428 NM3Q iNM32 0.1k434
NtA1 NM3 NM5 N1M7 NM9 N&Rll HUI 3 NMI5 NA417 »19
NM23 NtA25 NM27 N0A29 1«431 NU33 ttM35
Neutron monitors
Figure 2 : Ammal dose values of different neutron monitors
r--
166
IV.
9. TARr-, T -ICS
10. .- 3%.,E ERATOR C
TS
167
1..68
'ET PHYSICS
169
170
Evolution of a spallation reaction : experiment and Monte Carlo simulation (NESST).
M. Enke, C.-M. Herbach, D. Hilscher, U . Jahnke, 0 . Schapiro (HMI-Berlin) ; A. Letourneau, J . Galin, F.Goldenbaum, B . Lott, A . Peghaire (GANIL-Caen) ; D . Filges, R.-D. Neef, K. Nünighoff, N . Paul, H. Schaal, G.
Sterzenbach, A . Tietze (FZ-Jülich) ; L . Pienkowski (Univ . Warschau)
The need for reliable dato for the design and con-struction of spallation neutron sources such as the Eu-ropean Spallation Sonne (ESS) has prompted a renewedinterest in corresponding nuclear dato for thin as well asthick targets . Thin target dato provides insight into thephysics of the spallation process, the intra-nuclear cas-cade (INC) which leads to the formation of excited nu-clei subsequently decaying by evaporating predominantlylight particles such as n, p, and deportieies . The produc-tion of hydrogen and in particular of helium has strongbearings an the structural damages caused to the target-and or window- materials employed in the design of thetarget station . Reaction cross sections and productioncross sections for neutrons, hydrogen, and helium havebeen measured for 1 .2, 1 .8 GeV p + Fe, Ni, Ag, Ta, W,Au, Pb and U and are compared with different intra-nuclear-cascade- combined with evaporation-models [1].
-210 0
200
400
0 250 500 750 1000E* (MeV)
FIG. 1 . Comparison of experimental (solid dreies) and cal-culated (histogram) excitation energy distributions with thecondition of at least one evaporation-like detected chargedparticle for the reactions 1 .2 GeV p + Fe (left panel) and1 .8 GeV p + Au (right panel) . The solid, dotted, and dashedhistograms were calculated with the INCL, HERMES, andLAHET codes, respectively.
Exploiting the detailed exelusive dato measured atCOSY with the detector NESSI consisting of two 47r de-tectors for neutrons and charged partieles allowed for thefirnt time a systematic comparison with theoretical modeels during different stages of the temporal evolution of thespallation process : inelastic collision probability, excita-tion energy distribution (Fig. 1), pre-equilibrium emis-sion, and inclusive production cross sections . The com-parison with three different infraerillelear cascade modelshas shown that the excitation energy distribution repre-sents a critical Lest for the transition from the promptnuclear cascade to the statistical decay of the producedcompound nuclei . The calculated charged particle pro-
duction cross sections are particularly sensitive to thehigh energy tails of the excitation energy distributionwhile neutron production cross sections are less sensitive.Best agreement between calculated production cross sec-tions for H (below 26 MeV) and He has been obtainedwith the INCL-code, while the LAHET- and HERMES-code show Iarge deviations in particular for heavy nuclei(Fig . 2) . We associate this discrepancy with (i) the meanexcitation energy residing in the nuclei after the INC and(ii) different employed Coulomb barriers in the evapora-tion codes . Due to Iow statistics it was not possible in thepresent work to perform a detailed study of the variousIsotope ratlos -frequently exploited as thermometers- as afunction of dissipated excitation energies which, however,will be a challenge for future excIusive experiments.
Such experiments have been carried out at 0 .8, 1 .2,and 2 .5 GeV proton energies during two runs in 1999.In those runs also thin (500/a/cm 2) Au and U targetswere employed enabling to study fission as a function ofexcitation energy.
This work was supported by the HGF-Strategiefondsproject "R&D for ESS" and the EU TMR-project ERB-FMRX-CT98-0244.
[1] M. Enke et al . Nuel . Phys . A 657 (1999) 317.p(1 .8GeV)+X
043
2
0432
0
020
40
60
80
20
40
60
80Z
target
FIG . 2 . Experimental (Mied eimies) and calculated (solidline INCL, dotted line LAHET, dashed line HERMES) n, p(2 .2-26 MeV), d (2 .2-49 MeV), triton (t) (2 .2-76 MeV), 3 He,4 He production cross sections for 1 .8 GeV proton induced re-actions as a function of target atomic number Zearget . LCPcross sections were calculated for the experimental energywindows . Note different scales of left and right panels.
171
Neutron production in bombardments of thin and thick W g, Pbtargets by 0 .4, 0 .8, 1 .2, 1 .8 and 2 .5 GeV protons.
NESSI-Collaboration : A . Letourneau, J . Galin, F .Goldenbaum, B . Lott, A. Peghaire(GANIL-CaenM . Enke, D . Hilscher, U . Jahnke(HMI-Berlin);
D.Filges, R.-D . Neef, K.Nuenighoff, N .Paul, H.Schaal, G .Sterzenbach, A . Tietze(FZ-Jülich)
In the design of a neutron spallation source like theEuropean Spallation Saune (ESS), one of the key param-eters is the abundance of produced neutrons which de-pends on the nature and energy of the incident projectile,the nature of the target material, and the size and geo-metry of the lottert In a previous experiment at CERNsuch an investigation had been conducted essentially bymeans of secondary beams for a series of hadrons com-prising protons, deuterons, pions, kaons and antiprotons[Pie97, Hi198] . lt was concluded that the nature of theutilized hadron had rather little dependence on the neu-tron production but the determining parameter was theavailable energy brought in by this hadron . These datowere later complemented following low energy measure-ments also obtained with secondary hadron beams at theheavy ion facility at GANIL [Lot98].
The aim of the present COSY experiment was to en-rieh the previously obtained dato with the use of primaryproton beams with energies of 0 .4, 0 .8, 1 .2, 1 .8, 2 .5 GeV,bracketing more closely the energy envisioned for the fu-ture ESS. Also two target materials were studied (W, Pb)in addition to the foreseen Hg target which is at presentthe best choice for ESS. A large number of cylindricaltarget sizes have been explored, both in thickness anddiameter. The targets include thin targets in which a sin-gle reaction takes place and for which the primary IntraNuclear Cascade (INC) can be best probed and thick tar-gets for which Inter Nuclear Cascades can develop andthen be probed in addition. The development of the lat-ter depends strongly upon the size of the target and thisjustifies many different geometries to be explored . Al-together about 300 measurements have been performed,providing a wealth of experimental dato to be confrontedwith High Energy Transport Codes like HETC.
The originality of the present experiment lies in theevent-by-event measurement of the neutron muliplicity,leading to a neutron multiplicity distribution, a muchmore complete information than the average value whichis usually obtained in other types of measurements . Forthis purpose a high efficiency 4rr neutron detector, theBerlin Neutron Ball, has been used [Pie97, fli198] . lt is aGd loaded liquid scintillator detector which permits boththe measurement of reaction cross sections and of the neu-tron multiplicities . This Instrument has an unmatcheddetection efficiency of 82 .6% for the few-MeV neutronswhich constitute most of the leaking neutrons from thicktargets . A careful analysis of the dato taking into ac-count the energy of the emitted neutron has been mode,allowing comparison with simulations from the HERMEScode.
Fig.1 summarizes the basic information which hasbeen collected in this experiment .
!.
p+Pb
p÷Ilg
p+WA
*:
*
*
. 8
1---oev
t,, y
1*
1
10
Target thickness (1o 2' atornslem2)Figure 1 : Average neutron multiplicity per incident pro-ton as a function of target thickness (expressed in cm andnumber of atoms/cm2, for top and bottom panels, respec-tively) . Three material (Pb, Hg, W) and five energies (0 .4,0 .8, 1 .2, 1 .8, 2 .5 GeV) have been investigated.
lt shows the average neutron production per incidentproton over a broad range of target thicknesses, targetmaterial and beam energies . A more complete account ofthis work can be found in ref.[Let00].
The present dato could be complemented in a nearfuture by the energy distributions of both neutrons andcharged particles -induding the mesons- which have suf-ficient energies to leak out from thick targets.
This work was partly supported by the HGF-Strategiefonds project R&D for ESS and the EU TMR-project ERB-FMRX-CT98-0244.
ReTerences
[Pie97] L.Pienkowski et al ., Phys .Rev . C 56 (1997) 1909.
[Hi198] D .Hilscher et ah, NIM A 414 (1998) 100.
98] B .Lott et ah, NIM A 414 (1998) 117.
[Let00] A .Letourneau et a1 ., subm . to Inst .&Meth B.
0 .4 1 .2 2 .5 Ei GeV)n
Pb
o
A w* 0 0 Hg
bxt.
0
10 2
10
10
i 3 'o
: lnie
2 .5 GeV* 1 .8GeV
*
1 .2 GeV1' 0.8GeV
p.4 GeV 1 1
20
0
20
0
20Target thickness
172
E*-distributions following different intra-nuclear-cascade-models
NESSI-Collaboratidn : D.Filges, F .Goldenbaum, R .-D . Neef, K .Nuenighoff, N.Paul, H .Schaal, G .Sterzenbach, A.Tietze(FZ-Jülich) ; M. Enke, C .M. Herbach, D. Hilscher, U . Jahnke(HMI-Berlin) ; J . Galin, A . Letourneau, B . Lott,
A. Peghaire(GANIL-Caen) ; L. Pienkowski(Univ .of Warsaw), J .Toke, U .Schroeder (Univ .of Rochester)
In spallation physics the comparison of various cal-culated observables and simulated values resulting fromdifferent models on the one hand with measured valuesfrom experiments on the other hand serves to understandthe properties of hat excited nuclear matter . The exper-iments performed by the NESSI collaboration [Enke99]aim to clarify some of the still open questions in state-of-the-art Monte-Carlo codes currently used for the targetdesign of the European-Spallation Source (ESS) and in-tend to increase the predictive power of these codes whichare all based on the propagation of intra/inter nuclear cas-cades.
In the present contribution we focus on the cornparisonof calculated excitation energy distributions following theHETC[Ster98], the Cugnon code[Cug87] and the ISABELcode. HETC is a code based on the Bertini INC[Ber63]and currently used at Juelich; the Cugnon and ISABELcodes are also based on the INC-model, but follow thewhole cascade time-step wise . Comparisons with experi-mental results are presented elsewhere in this annual re-port.
Generally using HETC we observe excitation ener-gy distributions which are extending to larger energiesthan the distributions of Cugnon calculations do for thesame incident proton energy-as demonstrated in Figure1 . The effect is all the more pronounced the larger the
Figure 1 : E*-differential cross-sections for 0 .4, 1 .2 and 2 .5GeV p+Au reaction following calculations with HETC,Cugnon and ISABEL code.
energy of the incident proton is . Average values of theE*-distributions are summarized in Table 1 . The mainreason which could explain this disagreement between theCugnon/ISABEL and Bertini based INC codes is the way
Figure 2 : Kinetic energy spectra of lr - per unit lethargyand source proton for Cugnon and HETC codes for 1 .2GeV p+Au.
the originally transfered energy is being exhausted . Whilethe Cugnon code produees many relatively high energet-ic pions during the INC, the HETC code produees notonly fewer, but also less energetic pions as shown rep-resentative in Figure 2 for r- production following thereaction 1 .2 GeV p+Au. Consequently the available ther-mal energy right after the fast cascade is smaller for theCugnon calculation. Taking out the effect of different pi-on contributions during the INC the codes HETC andCugnon seem to agree . This has to be confirmed by de-tailed calculations. The question whether these differentmultiplicities and energies of pions are matter of a differ-ent basic approach-enabling a different pion productionmechanism-or whether more sophisticated fundamentalcross sections in the Cugnon code are responsible can cur-rently not yet be answered.
Table 1: Mean values of E*-dist . shown in Fig .1.proton energy
0 .4 GeV 1 .2 GeV
2 .5 GeV
Cugnon-code 71 MeV 192 MeV 246 MeVHETC 117MeVJ 282 MeV 432 MeV
This work was partly supported by the HGF-Strategiefonds project MD for ESS and the EU TMR-project ERB-FMRX-CT98-0244.
References
[Enke99] M .Enke et al ., Nucl .Phys . A, Volume 657, 317(1999).
[Ster98] G.Sterzenbach et al ., 2nd International Topicalmeeting on nuclear Application of Accelerator Tech-nology, AccApp98', Getlinburg, Sep . 20-23, 1998, IS-BN 0-8944 8-633-0.
[Cug87] J .Cugnon et al ., Nucl .Phys . A470, 558 (1987).
[Ber63] H .W.Bertini et ah, Phys .Rev . 134, 1801 (1963).
CUCNONHETC
g 0.16
0.14
0J2 [-
ä0.
114 0.080.060.04
z 0.02-in 1 »nii'11t1 i
1
10
10 2 103
>**
E [MeV]
,r
173
Progress on JESSICA
H. Bamert-Wiemer, M . Butzek, H . Conrad, D. Filges, F .Goldenbaum, B . Haft, G . Hansen, R. D. Neef, N . Paul,C. Pohl, H . Stelzer, H . Tietze-Jaensch, U . Ullmaier and the JESSICA international collaboration
Wall JESSICA (Fig . 1), ESS-type target, reflector andmoderator mock-up, another major Jülich based ESS aetiv-ity was hüdate& The proposed design concept [1-6] wasintroduced to the COSY Programme Advisory Committeeand received a unanimous welcome statement and support.In 1999 an international collaboration was established withsubstantial support from 12 leading edge neutron researchlaboratories from around the globe . Subsequently two col-laboration meetings were held in Jülich [5] and Ancona [7]where many conceptual details were developed, discussedand refmed. In general, the JESSICA design mimics theESS [8] . Spallation neutron target and moderator efficiencyperforrnance expelirnents at the integrated JESSICA set-upare consequently pursued to utmost resemble ESS-likeconditions . A maximurn flexibility of any of the individualcomponents is pursued, also, in order to experimentallydetermine the physical parameters of JESSICA and, mostimportant, to benchmark Monte Carlo sirrmlation codes andMC computer code systems for an overall thorough com-putational refmement of the final ESS target, reflector andmoderator design.For experiments on JESSICA the COSY accelerator de-livers a short pulsed proton beam of variable energy be-tween 03 and 2 .5 GeV. Thus, JESSICA will be the fastapplication of COSY in its pulsed mode of operation. Thisis clearly beyond the initial design purpose of COSY.Proton pulses of <1 pulse width were extracted into theJESSICA beam line at an energy of 300 MeV, the maxi-murn energy under the 1imits of the old existing radiationand Operation license for die JESSICA ca .vera . Meanwhile,this license was upgraded to the fein extent of die COSYenergy and intensity . Shortly after permission was grantedby the authorities the installation had cornrneneed in earlyDecember 1999 . Back-end shielding needed to be enforced,interlocks, mains and service utilities are modified.By varying the geometrical conditions and coupling pa-rameters as well as the chemical constitution of the mod-erator, JESSICA provides an ideal experimental test bed forscrutinising different types of moderators . Thus, theJESSICA collaboration has established dose links with theACOM international collaboration [9] working on the de-velopment of high intensity, high resolution advanced coldmoderator concept suitable for high-power spallation neu-tron sources in die US, Japan and EU . For this, JESSICAprovides a unique facility to investigate the neutron Per-formance of advaneed moderators at very realistic condi-tions of an 1 :1 ESS-type integrated target and reflector set-up with lots of possibilities of geometric fme-tuning, pre-moderation devices, (de-)coupling sheets, even theconsiderably easy installation and utilisation of a compositereflector with an inner shell of Be is made possible withJESSICA and due to the advantages of the comparablyweak intensity COSY proton beam, all düs is made possiblewithout the hasste of high activation levels, the needof excessive biological shielding and, last not least
Fig . 1 : 3D design cut of JESSICA
without radiolysis effects in die moderator to be tested.Hence, JESSICA has attracted considerable internationalattention and support.A specific grant from the BMBF was received to enableRussian colleagues and engineers to Jong tenn visitJESSICA and perform developing tasks on site . Further,based on EU-TMR grants, two Ph .D. students commencedtheir work on numerical calculations of the neutron tarn-pon from target to moderator . Using the HE ES and LCScode systems the particle production and neutronevaporation is calculated . A modelling of the JESSICAtarget station, reflector geometry and size of the varioustypes of moderators, such as ambient water, liquid hydro-gen, liquid and solid methane were calculated . The resultsof the thermal neutron flux density calculation well resem-ble the Maxwellian contribution for a stationary calculation,whereas the time dependent simulation displays the differ-enees in efficiency of various types of moderator materialsfor their thermal neutron flux density speetrum [10].References:[1] R. D. Neef, Proc. ICANS XIV, ANL-98/33 (1998)
441[2] B. Alefeld et al ., COSY PAC prop. #76, Jülich (1998)[3] H. Tietze-Jaensch, Physica B (2000), accepted for
publ.[4] D. Filges & H . Tietze-Jaensch, ESS 99-98-T, (1999)[5] D. Filges et al ., Proc . AccApp, USA (1999)[6] http :llwww .fz-juelich .de/ess/INT/JESSICA/JESSICA.
htm1[7] H. Tietze-Jaensch, ESS 99-99-M-4 (Feb 2000)[8] G. S . Bauer et. al ., The ESS Study, Vol . 111,
ESS-96-53-M (1996)[9] http ://ww-w.fz-juelich .de/ess/INT/ACOM/ACOM.htrn1[10] C . Pohl, Thesis, U . Wuppertal (1999)
1.74
Apparatus to Study Proton-Induced Spallation
The PISA Collaboration
Experiment to measure total and differential crosssections for proton-induced spallation of different tar-gets at several energies will be performed at the inter-nal COSY beam . Such data are of crucial interest fordesigning targets and shielding of the European Spal-lation Source . Quantitative estimation of structuralchanges of the irradiated materials can be performedonly with the use of simulation codes [1], which inturn raust be based on firm experimental dato . Totest quality of the spallation reaction models underly-ing such calenlotions it is necessary to confront themwith a possibly wide spectrum of experimental dato,in particular the energy and angular distributions ofthe cross sections are highly demanded . Unfortu-nately, at present such complete sets of observablesfor the spallation reaction are very scarce [2] ; virtuallyno dato exist for coincidence measurements of protonswith the heavier spallation products . Obviously suchdeficiencies call for further experimental efforts.
Experimental determination of the spallation crosssections for C, N, 0 targets will provide a valuabledato, set to improve our understanding of the anoma-lous abundance of light elements in the cosmic rays.Isotopes of Li, Be and B are predicted to be by 5-6orders of magnitude less abundant than found in theGalactic cosmic rays . Similar underestimation is alsoknown for the elements with atomic numbers 20-25.Most plausible explanation of Chose discrepancies isbased on spallation origin of elements [3, 4] . However,to account for all details of the relative abundances ofall isotopes on the ground of astrophysical models it isrequired to thoroughly test their predictions . There-fore not only the values of the total cross sections, rele-vant in the content of the abundance problem, have tobe deterrnined experimentally, but also the cross sec-tion energy distributions should be known preciselyenough to allow checking of the full content of the ap-plied model . There is, however, a serious lack of suchdato in the intermediate range.
In our experiment we are going to induce spallationof various targets (C, N, 0, Al, Si, Fe, Ag, Au) withthe COSY proton beam of few energies between 100and 2500 MeV . The spallation products will be un-ambiguously identified (both A and Z) by combinedtime-of-flight and Bragg curve determination tech-nique . The design of the experimental apparatus isshown in Fig . 1 . Vacuum chamber, containing the tar-get holding/changing mechanism, is connected with 8identical detection arms . In each arm two multichan-nel plate detectors with very thin electron-emitting
Figure 1 : Scheine of the experimental apparatus . Po-sitions of flanges for the multichannel plate detectorsand locations of the Bragg curve and phoswich detec-tors are shown together with some other elements ofthe vacuum system . Angular setting of every arm isindicated.
carbon foils are used for TOF determination on thebasis of about 30 cm flight path . Their resolutionshould allow to identify masses up to A ,', 'r. 20 . Chargeidentification and energy determination will be per-formed in the Bragg curve detector (gas ehamber),following the TOF telescope . Details of the Braggdetector construction and results of its tests are pre-sented elsewhere in this Annual Report . Additionaladvantage of applying such detector configuration islow energy threshold for the registered ions, of about1 MeV/nucleon . To detect protons from the reactionas well as their coincidences with the ions each armwill be closed with the scintillation phoswich detector.
References[1] J . Cugnon, C . Vollant, S . Vuillier ; Nucl . Phys.
A620 (1997) 475.[2] H . Ullmaier, P . Carsughi, Nucl . Instr . Meth.
8101 (1995) 406.[3] H . Reeves, Rev . Mod . Phys . 66 (1994) 193.[4] R . Silberberg, C .H . Tsao, Phys . Rep . 191 (1990)
351.
175
Development of the Bragg Curve Detector for the Spallation Products
A . Budzanowski 2 , D . Filges, L . Jarczyk l , B . Kamys l , K . Kilian,M . Kistryn 2 , St. Kistryn 1 , H . Machner, A . Magieral , W. MigdaP, K. Pysz 2
In the experiment in which total and differentialcross sections for proton-induced spallation of differ-ent targets will be measured [1], the energy and chargeof the spallation products will be determined withthe use of the Bragg curve detectors . In the stud-ier of the multifragmentation processes, it has beenshown [2] that such detector enables identification ofisotopes from Li to Ti with an energy threshold ofabout 1 MeV/nucleon . By appropriate tuning of theoperating conditions it is also possible to identify Heions, keeping the Iow detection threshold [3].
The prototype Bragg curve detector has been de-signed, built and optimized in the dedicated detec-tor laboratory of the Institute of Physics, JagellonianUniversity in Cracow . Construction of our counter,shown in Fig . 1, is based an well known configuration[4] . Gas volume of the counter (18 cm length, 5 cmdiameter) is closed by 3 sm thick metalized mylar foilsupported by wire mesh, used as cathode, and by theanode (printed board in the prototype) . The Frishgrid, defining the ionization sampling section (2 cmfrom the anode), is made of 20 pm gold-plated tung-sten wires with 1 mm spacing . The voltage betweenthe cathode and the Frish grid is divided by a resistorchain connected to 9 field shaping rings which pre-serve a homogeneous longitudinal electric filed overthe active detector volume. The detector is filled withisobutane and operated at about 200 Ton pressure.
z-
Figure 1 : Design of the Bragg curve detector for de-tection of the spallation reaction products .
The best operating conditions of the counter hauebeen chosen in the course of tests with alpha par-ticles from the radioactive sources . The ability ofcharge identification has been tested by using few ionbeams with energies of 1-2 MeV/nucleon from the cy-clotron of the Heavy Ion Laboratory in Warsaw . Fi-gure 2 shows an example of the Bragg-amplitude (Z-identification) spectrum obtained for 4 He (radioactivesource), 12 C and 160 ions. Excellent separation of thepeaks proves that the required performance of the de-tector is achieved . Further tests with richer sample ofvarious ions with different energies are performed withthe use of ion beams from the Tandem accelerator inCatania .
DISTRIBUTION BRAGG PEAK AMPLITUDES700
6
s
400zo
30
2
100
Figure 2 : Identification spectrum for three sorts ofions registered in the Bragg curve detector . The peakscorrespond to 4 He (left), 12 C (middle) and 160 (right-most) ions . Separation of peaks along abscissa reflectsthe ability of the detector to resolve various chargesZ of ions.
References[1] PISA Collaboration Contribution to this Annual
Report.[2] K .H. Tanaka et al ., Nucl . Phys. A585 (1995)
581c.[3] P.N . Andronenko et al ., Nucl . Instr . Meth.
A312 (1992) 467.[4] J .M. Asselineau et al ., Nucl . Instr . Meth. 204
(1982) 109.
1 Institute of Physics, Jagellonian University, Cracow,Poland2 Institute of Nuclear Physics, Cracow, Poland
_soso=O.,Os.44,4
CATHDDE
r
FIELDS PINGRINGS
.... ... .. .... ...
... .... .. ... ... .. . . .. .... ... .. .
.... ... ... ... ... .
... .... .. ... ... ... ... .. ... ....
.... ... ... ... ... .
. ... ... .. ... ... ... ... .. ... ... .....
0 .5
1
1 .5
2BRAGG PEAK AMPLITUDE (ARBITRARY UNITS)
. . . . . ... ... .... .. . ... . .
. . . . . . . .. ..
176
Status of TETHYS
A . Boudard', J .E. Ducret', S . Leray', Y. Terrien', C . Volant'J. Frehaut', X. Ledoux 2 , P. Patin, P. Pras 2
D. Filges, F. Goldenbaum, K. Kilian, H .P. Morsch, R.D. Neef, E. Roderburg, H . SchaafG.D. Alkhazov 3 , A .V. Kravtsov3 , A .N. Prohohe-0
W. Augustyniak4 , P. Zupranski 4P.A. Strokovsky5 , J . Cugnon'
Our collaboration has proposed to install at COSY theTETHYS detection system.The physics goals we emphasize are twofold i," and maybe summarized as follows:
1 . Spallation physics
a. Measurement of inclusive charged particle spectra(mainly protons and pions) emitted from spallation re-actions an thin targets with systematics on target massand proton beam energy.
b. Coincidence measurements of fast charged particleswith a neutron multiplicity detector.
These measurements should give inside into the natureof the initial interaction (collective effects, importance ofthe degree of freedom. . .), test of intra-nuclear cascademodels and the time scale when evaporation is reached.These studies aim at detailed tests of the presently avail-able spallation codes to be used for the design of futurespallation sources.
2 . Study of N* resonances and nucleon structureaspects
a. Measurement of exclusive N* production in proton-aand proton-deuteron scattering.
b. Measurement of N* effects in p induced 2rr produc-tion, heavy meson production.
These studies should give detailed information on thestructure of N* resonances, which is complementary toinvestigations with electromagnetic probes . A very im-portant point of our investigation is the study of a-pinteractions from which the 'scalar' structure of the nu-cleon can be deduced . This is a continuation of our ex-perimental investigations at Saturne i .Detailed experimental information is urgently needed totest structure models of the nucleon.
Due to the Zarge magnetic gap of TETHYS the above re-actions can be studied in a 'arge solid angle and a goodmornentum resolution . Because of the good performancethis detector may be well suited also for other investiga-tions related to medium energy physics .
A schematic view of the detector is given in fig .1 . Themain components of the system are:
1. C-magnet with gap Im . Im . 0 .5m and maximum fieldof 1 .4 T.2. Target stations for solid targets in air and liquid Hand He targets in vaeuum.3. Segmented start scintillation detector dose to the tar-get station.4. Forward detection system with 6 planes of multi-wiredrift chambers and hodoscope wall.5. Lateral detection system with multi-wire proportionalchambers and scintillation hodoscope wall.6. Recoil detector telescope (finely granulated Silicon p-strip detector) behind the target in vacuum . This willbe used mainly for the investigation of N* excitation inp-a scattering.7. Neutron ball in front of TETHYS for the study of Iowenergy neutrons . This detector will be used for spalla-tion experiments to detect Iow energy neutrons coinci-dent with fast protons.
Figure 1 : Schematic design of the detector with magnet,forward and lateral detection system.
177
The PAC as well as the recent COSY review commit-tee have recommended the installation of TETIIYS atCOSY . The installation of TETHYS is forseen in theCyciotron east hall . For this a new beam live has tobe build . The magnet as well as the existing detectorcomponents, multi-wire chambers and scintillation wallswill be transferred from Saturne to COSY in sping 2000.The entire set-up of the detector should be completedwithin the next two years, so that commissioning andfirst experiments can start in 2002.
Concerning N* physics the review committee has ex-pressed its wish to discuss this program in the contextof the renewed interest the investigation of N*'s, tosee if the proposed program is significant, competitiveand complementary to the worldwide N* program beingperformed mainly with electromagnetic probes . For thiswe will organise a workshop an "Baryon Excitations"beginning of May 2000 at Jülich.
1 SPhN Centre de Recherche Nueleaire Saclay, France2 CEA Bruyeres le Chätel, France3 St. Petersburg Nucl . Phys . Institute, Gatchina, Rus-sia
Soltan Institut for Nuclear Studies, Warsaw, Poland6 JINR Dubna, Russia6 Universite de Liege, Belgium
References:
1. COSY proposal No 73 .1 "Spallation physics: mea-surement of light charged particle cross sections andstudy of reaction rnechanism", spokesmen A. Boudardand D . Filges
2. COSY proposal No 72 " Exclusive study of N* reso-nanee excitation using a lange solid angle magnetic spee-trometer" spokesman H .P. Morsch
3. H .P. Morsch and P. Zupranski, Phys . Rev. C (2000)in print ; and IKP annual report 1999
178
1 0 . ACC E ATu 0 PON
179
180
Field-Profile Measurements at a 5-Gap Crossed-Spokes Model Cavity
Gb. Schug, Ch. Deutsch, B . Da en, D . Gehsing, A . Riehen, M. Schaaf, H. Singer, K . Sobotta, R . Stassen, E . Zaplatin
AbstractA copper model of an alternative accelerating cavity wasdesigned for ESS proton energies around 120 MeVoperating near 500 MHz . The longitudinal E-fielddistribution has been measured using perturbationtechnique.A field flattness within has been reached by tuningboth end plates . The predicted fields using MAFIAcaiculations agree with the measured data within a fewpercent.
Fig. 1 : 5-ges crossec4pokes cavity
Model cavity
Fig. 2 : Field measurement set-up
A crossed-spokes cavity (Fig.1) was studied as anaccelerating structure for medium ESS energies. [1] Thecircurnferencial wall of the model cavity (Fig .2) wasmachined out of a commercial brass pipe, the spokes andthe end plates are of copper . The RF contacts to the wallsvia spiral springs . Tab . 1 gives a short parameter list.
Tab . 1 : Crossed-spokes cavity
accel .-mode frequeneyfield modenumber of spokesnumber of cellsinner-cellIengthgap lengthcavity inner lengthcavity inner diameterbeam-hole diameterunloaded quality factor
461 MHzpi45
150mm105mrn
1050mm316mm60mm
5000
nominal proton energyrelative proton velocity vlccell-to-cell couplingproton cell-transit-t. factor T
120 MeV0.46
- 20%- 0.75
1 : cavity wall (brass), 10 : spindle bearing 17 : RF-coupling loop,2 : vertical spoke (45 mm thickness), 11 : thermal shield,3 : horizontal spoke (45 mrn thickness), 12 : support, 18 : support for sheaves,
beam holes (60 mm) 13 : cavity hold, 19 : retum sheaves,drift tubes, 14 : perturbing bead (Al), 20 : 5-phase stepper motor,
6 : adjustable short, driven by spindle, 15 : string, 21 : string driving wheel7 : sliding rod, 16 : spring, (impregnated wood)
nut, 22 : angle decoder.9 : spindle,
181
The pi accelerating mode is the First resonance of a seriesof 5 circular-H-11 like modes, identified at the RFtransmission between two coupling loops at the cavity . Atransmission loss of 25 to 30 dB was reached at theresonances . The positions of the adjustable shorts had beenoptimized for the accelerating mode . The resonantfrequencies of the first 5 modes as calculated by MAFIA[4. . .6] and as measured are tabulated in Tab .2.Calculations for a quarter of the cavity used a 100 11' 11point mesh. That was sufficient to determine of the eigenmodes with a precision better than 1 % and the fielddistribution within ±0,1 % . (The lauer precision for thefrequency would require 2 000 000 mesh points an doubleprecision; this would lead to a run time of 30 h .)
mode frequencies MHz Q,j1000M
A Measured measured463 459 .84 5 .5475 470 .34 6495 490 .48 6534 530 .12 6595 589 .96 4
Tab . 2 : Calculated (100 000 mesh points) and measuredfirst eigen modes of crossedsspokes model cavity;positions of the adjustable shorts:MAFIA : 82 mm, measurement : 84 mm
Measurement set-tmThe model cavity is connected via two coupling loops to anetwork analyzer (Fig . 2) . A bead of 6 mm * 3 mmdiameter was used to determine the longitudinal electricalfields by the perturbation technique [3] . The RF phasedeviations of the transmission factor were measured nearthe resonance (resonant perturbing method, cf. [4],transmission loss of 25 to 30 dB, generator power level+20 dBm of network analyzer) . The small bead allowed ahigh spacial resolution but it required a thermal stability of± 0,2 K, corresponding to a fluctuation of the resonantfrequency of <50 Hz . Therefore, the following thermalstabilizing measures were applied :
thermal insulation of the driver motor,• shifting the motor away from the string wheel by 20
cm,• thermally shielding the cavity• stabilizing the room temperature.Also, the bead-pull dato have been evluated in onedirection only. The perturbations by the driving stringsamount to similar values as that of the bead, but theirdensities depend an the mechanical tension of the strings.The friction forces at the retum sheaves are different forboth directions and hence the tensions.
Measurement control systemThe computer control had been designed using theexperience of the COSY control system [7].Fig.3 gives an overview of the computer control of theperturbing-bead drive and RF-measurement set-up:
• GO4 system for local control of motor power driverincluding brake, end contacts and angle-read-out, air-mesurement system and other peripheral units,RF network analyzer hp 4396,
. a workstation hp 715 for the application programmingSystems like TCL, VEE, RTOS working under theOperation system HPUX and connected to the internalIKP net,
• a separate LAN for measurement control.
Field-profile measurementsThe start positions of the adjustable shorts (Fig .2) hadbeen calculated to be 82 mrn for the accelerating mode Thedashed curve in Fig.4 shows the longitudinal E,distribution as determinated by MAFIA . The maximalamplitudes agree within ± 3 %.The experimental optimization of the skort positions led to84 mm by synchronously tuning both end plates ; thecorresponding field profile is given by the solid line inFig .4 and shows a field flattness within ± 6%.The field distributions of the 4th and 5th mode in Fig .5demonstrate the preference of the Ist mode.
u
MAU1ov:ei LAN
RF-NetworkonotyserMP 4396
per b ' b od
AN Gpe
RF-Coupling
Crossed-spokes resonotor PrinterT p
eoir
s e
RS 232
6box
v
HP 71UMWork-stationLAN I
Ends ch
0r
sslEncoder
0KP-LAN
u
XVEETCLRTOS
IKP/spoke sblock 26 .01 .00
Fig .3 : Control system for bead-pull measurements
182
ah ,
quaters1001<82el und
grKo.IB22112-mode5 normiert Waxed threads deposited wax an the reels . That led toboth ehanging densities and unstable friction forces atthe reels.
The perturbations by the different strings mostly exceededthat of the bead, and their density fluctuations of 10 to 20% invalidated the bead perturbation data.A thread of 0.5 mm diameter used in tuning drives tumeclout to be most suitable driving string. This thread has astrain-hardened core and a woven cladding.Using that experience, future examinations will also lookat the higher field modes, especially the pi mode of the 5first E-01 like modes, e .g the field flattness and thesensitivity to tolerantes and contact resistances . Inaddition, we will develop suitable configurations for high-power RF coupling into the spokes resonators.
Fig .4: Relative accelerating-field profiles of the pi modeOf the model cavity, measured E, field, numerically temperature
compensated, short positions : 84 mm; MAFIA calculated E, field, 100 000
meshpoints per quarter of cavity, shortpositions : 82 mm
Fig .5 : Relative accelerating-field profiles of the 4th and5th mode of the model cavity measured and
calculated E, Fields
Problems and future worksThe remaining thermal instability requires furtherdevelopment:e The average power loss (-50 W) of the stepper motor
will be lowered by reducing the motor currents atstandby . The Berger motor-driver crate does notforesee a prograrnmable camp-down of the motorcurrents.The motor phase currents should be changed tosinusoidal wavefonns . So, mechanical excitations ofbead and string will be minimized . This leads to ap ower measuring time per step.
• The survey time will further be reduced by introducingball bearings into the retum sheaves instead of theplain bearings . This mechanical tensions of the stringwill be more syrmnelrie with respect to bothdirections . Possibly, both directions could so be usedfor field measurements.
Different String material habe been investigated:
• Single-fibre Perlon or Nylon strings had stretched andled to irreprodueible postitions . The stick friction atthe string driving wheel was insufficient, and madethererfore the Slip non repeatable.Sewing threads were irregularly abrased, whichresulted in an inhomogenious density .
Ackno d en sWe are greatly indebted to our IKP colleagueU. Rindfleisch for design and the IKP workshop formanufacturing and assembling.
References[1] E. Zaplatin, W . Bräutigam, S .Martin, Design study
for SC LinAc cavities, Proc . 1999 PAC, N .Y ., 1999,p . 59 . . .61 similarly in IKP Ann . Rep . 1998, Jü1s3640,FZ Jülich, Feh . 1999, p . 195
[2] Müller, Johannes, Untersuchungen über elektro-magnetische Hohlräume, Z .H .E . 54 [1939], 157 . . .61(Slater had published the energy-perturbing formulamore than 10 years later .)
[3] Peschke, Claudius, Messungen und Berechnungen zulongitudinalen und und transversalen Shuntimpedan-zen einer Elektronen-Positronens Linearbeschleuni-ger-Struktur, Diplomarbeit im Fach Physik, IAP, J .-W.-Goethe-Univ ., Frankfurt/Main, Jan . 1995
[4] R.Klatt, F.Krawczyk, W .-R . Novender, C .Palm,T.Weiland, B .Steffen, T .Barts, M.J .Browman,R.Cooper, C .T .Mottershead, G .Rodenz, S .G.Wipf,MAFIA - a three dimensional electromagnetic CADSystem for magnets, RF structures, and transientwake-field calculations, 1986 LAC Proc .,SLAC Rep. 303 [Sep .86], p . 276
[5] F.Ebeling, R.Klatt, F.Krawczyk, E .Lawinsky,T.Weiland, S .G.Wipf, B .Steffen, T .Barts,M .J .Browman, R .K.Cooper, G.Rodenz, Status andfuture of the 3D MAFIA Group of codes, DESYM-88-15 [1988] and pp. 117 . . .130 in Charles H.Eminhizer (Ed.), AIP Conf.Proc . 177 : LinearAccelerator and Beam Optics Codes, APP, La JollaInstitute, N .Y., 1988
[6] CST-Gesellschaft für Computer-SimulationstechnikmbH, MAFIA 4 Tutorial (Getting started, a guidedtour through the most co an features of MAFIA),May 1997
[7] K.Henn, M. Schaaf, M .Simon, New design andimplementation of the COSY-control operatorinterface, IKP AnnRep .1995, Jül-2952[Feb . 1996], p . 255
183
Study for a combined Preaceelerator Complex for COSY-ESS LinacK. Bongardt, W . Bräutigam, J . Dietrich, R . Maier, S . Martin, A . Schnase, P . v .Rossen, R . Tölle, E . Zaplatine
AbstractA feasability study is shortly described for building at the
FZI a combined COSY-ESS linear accelerator facility . Theaim of the study is to find a cost effective approach for thetwo quite different linac requirements.
An injector linac for COSY needs only to provide a lowintensity H- and D- beam at 70 MeV with a pulse lengthshorter than 0.5 ms and less than 10-3 duty cycle . As theCOSY injector linac has to operate at least 7 h p .a, alinac frequency about 200 MHz is preferred to make use ofexisting RF tetrode systems and increase efficiency.
In contrast, the ESS test linac needs a chopped highintensity H- beam with 50 Hz rep . rate and at least 0 .5 mspulse length . The frequency at high energies should be nearby 700 MHz to allow beam tests for 3 = 0.5 ESSsuperconducting elliptical multicell cavities.
As a compromise the first paff of the combined COSY-ESS linac operates at 233 MHz, whereas thesuperconducting cavities are designed for a 3 times higherfrequency of -700 MHz.
Description of the COSY-ESS linacThe combined COSY-ESS linac arrangement is shown in
fig . 1 ., the parameters of the main IH linac are given intable 1 [1].
The combined COSY-ESS linac starts with twoindependent front end systems, followed by a co anmain linac which starts at 2 .5 MeV/n. The arrangement ofthe two independent injector branches allow to test the highintensity ESS beam, including Operation of the 2 .5 MeVchopping line, without disturbing the Operation of the
COSY injection linac. Handling of a D - beam in the mainlinac is achieved by using a higher gradierst . Using 216MHz IH structure like the one planned at the HeidelbergGerman Cancer Therapy Facility could be a very costeffective alternative. A pulsed switeh yard magnet allows toinject either polarised particles into COSY or to performhigh intensity beam tests of the 50 Hz pulsed ESSsuperconducting cavities . For a polarised H- ion sourcecurrent of 300 and a 500 p.s pulse length, more than1011 polarised H- particles can be offered for COSYinjection.
Energy at injection
2.5 MeV/uEnergy at extraction
70 MeVFrequency
233 MHzTotal length
25 MDrift tube aperture
30 MmLens aperture
33 MmCavity Lose W
5.5 MWCavity Lose D-11 MWMax. beam power
3.5 MWNormalised input emittance
2 7rmm mrad
Tab. 1 : Brief parameter list of the 233 MHz IH Proton /Deuteron Main Linac
[1] The Preaccelerator Complex for COSY and its Relationto the European Spallation Source Project, Concept Study,21 .6 .1999, Internal Report IKP
Preaccelerator ComplexFunctional Groups
Intensity Ion Sources:
, D' polarized
Energy1 Transport
Low intensity RFQ233 MHz
2 .5 MeV ff , D-400 pA0 .1% duty cycle
70 MeV
>70 MeV50 mA
50 mA
40 keV500 siA
'narverHigh intensity
lr Source
Low EnergyBeam Transport& Prechopping
lEgh IntensityRFQ {H')233 MHz
ChopperIn
ationCavity TestLine 700 M
High EnergyBeam Dmnp100 MeV<350 kW>
2 .5 MeV50 mA
10% duty cyele
. 2.5 2vreV
Beam Diagnostics 70 MeV lr D'40 ke V70 mA
2.5 MeV
COSY InjectionN < 10'2 ppp
Fig . Functional groups of the COSY-PSS preaccelemtor complex
naer (HO
184
Beam Lass Studies for the ESS ltteeeierotor Complex
K. Bongardt, M . PahOt l , A. Letchford2
AB STRACTThe 5 MW accelerator complex of the European SpallationSauce ESS consists of a full power H-injector linac,followed by 2 compressor rings at 1 . 334 GeV. The maindesign issue is to avoid activation at the linac end and toguarantee loss free ring injection afterwards . Unconstrainedhands an maintenance requires less than 1 W/m lost beampower at high energies.Particle loss is caused by the development of a halo aroundthe dense beam core . Only halo particles in real space cancause activation. Loss free ring injection however requiresan unfilamented phase space distribution at the linac end.The major source of halo formation is mismatch caused byquadrupole and RF field mors, enhanced by the periodicfocusing scheme and temperature exchange . Monte Carloresults are presented for high intensity mismatched bunchedbeams, showing strong halo formation in axial direction dueto resonance crossing.Phase space distributions are shown at the end of the214 rnA, 1 .334 GeV ESS linac for the reference layout andan improved one, leading to significant halo reduction forthe mismatched case.Simultaneously correction of accumulated linac energy shiftand reduction of energy spread by placing a bunch rotator inthe linac to accumulator transfer line is demonstrated for aby 20 % mismatched beam at 70 MeV, superimposed by 3MeV energy shift at the linac end . After bunch rotation, allparticles are well inside the ± 2 MeV energy spread limitfor lass free ring injection.
Halo Formation of Mismatched Bunched Beams in PeriodicFocusing ChannelsThe major problem of the design in high current protonlinacs is the loss of particles at higher energies . In a linaclosses occur radially due to the formation of a beam halo.The beam halo consists of a 'small ' number of particles,which oscillate around the beam core.In recent years substantial progress has been achieved byidentifying the parametric resonance condition as a majorsource of halo production for DC and bunched beams . / 1 /For realistic particle distributions with non-linear spaceeharge forces particles even inside the core have a tunespread . Parametric resonances can occur between singleparticles tunes and the frequency of the oscillating mis-matched beam core, see Appendix.In a periodic focusing channel additional resonances andinstabilities, which don't exist in a uniform channel, caninfluence the single particle motion.One is the envelope-lattice instability, which occurs for ahigh mode frequency nearby 180° . The instability leads toan increase of the rrns envelope.A 90° particle lattice resonance can be excited either bytemperature exchange or by mismatch even for modest tunedepression around 0 .8 . Here a few particles are expelled faroutside the dense core . / 2 /
0
20
40
60
80
100
120
140
160
PeriodFig . 1 : Phase values of the outermost particle generated by a90° particle - lattice resonance and by a 30 % mismatch.Broken lines: the mismatched bunch size of ±18°Solid lines : twice the mismatched bunch size of ±36°
In Fig. 1 phase values are plotted for the longitudinaloutermost particle of a mismatched but equipartitionedbunched beam in a periodic focusing channel . The initialtransverse and longitudinal tune depressions are about 0 .77.A pure 20 % transverse and 30 % longitudinal high modewith an analytical phase advance of 166° drives singleparticles into the near by 90° longitudinal particle-latticeresonance as the longitudinal zero current tune is just above90°. The in Fig. 2 shown outermost particle leaves themismatched bunch after 60 focusing periods and is outsidetwice the initial mismatch bunch size after 160 focusingperiods . Its longitudinal tune is nearby 90° after 60 focusingperiods, leading to an oscillation through the bunch core in2 periods.
In Fig . 2 two dimensional phase space and real spaceprojections are shown for the same bunched beam transfer-line as in Fig . 1, but here exciting strongly a pure 33 %transverse and 50 % longitudinal high mode. After 160focusing periods substantial halo formation is visible in thelongitudinal phase plane associated with radial-axialcoupling of the outermost halo punzlest These particles aredefinitely outside twice the initial mismatched bunch size of±42°. No filamentation occurs in the transverse planes, asexpected for a transverse zero current tune of 85°.
Fig. 2 : Strong hala formation generated by a 90° particle-lattice resonance and 50 % mismatch
185
Results for the ESS Linac
During the start-up period of a high intensity
injectorlinac, much more transverse and especially longitudinal
mismatch is expected as for a proton linac . The beam istransversely mismatched and filamented injected into RFQ1 as a consequence of space charge neutralization problems.Same longitudinal mismatch is unavoidable in the choppingline with its more than 5 rebunching cavities ./ 3 /Quadrupole and RF field errors in the followingaccelerating sections will enhance phase space filamentationdue to exciting all 3 mismatched bunched beam modes . Fora high intensity bearn, field errors even in a singlequadrupole doublet resp . a single RF cavity are not excitinga pure transverse resp . longitudinal oscillation of thebunched beam envelope, see Appendix . As a consequence,transverse and longitudinal phase space filamentation willresult afterwards for both cases.
For H - injector linacs with its constraints due to loss freering injection a design is required with only small 6d phasespace filamentation at the linac end . / 4 /In Fig . 3 phase space distributions at 1 .334 GeV are shownfor the 214 mA ESS 700 MHz CCL / 5, 6 with a 20 %quadrupolar mismatched beam at 70 MeV CCL injectionenergy . The upper plots are for the ESS reference designwith its 102° transverse zero current tune at 70 MeV . Thelower plots are for an improved ESS CCL layout with only92° transverse zero current tune at 70 MeV. / 2 / Clearlyvisible is the quite substantial decreased halo formation inall 3 phase space planes for the improved ESS CCL layoutwithout resonance crossing . The not shown phase spaceplots for a matched input beam at 70 MeV are almost thesame for both designs at 1 .334 GeV linac output energy.
Fig . 3 : Phase space distribution at 1 .334 GeV linac outputenergy for the ESS reference layout (upper graphs) and animproved layout (lower graphs) . A 20 % quadrupolar modeis excited at 70 MeV.
The bunched beam envelope instability and crossing a 90°particle-lattice resonance, either transversely or longitu-dinally, has to be avoided. Linac designs with both tunedepressions above 0.8 and transverse to longitudinaltemperature ratios between 1/3 and 2 are proven to be in-sensitive against all kind of mismatch. Space chargedorninated linac designs with tune depressions below 0 .4 orlarge temperature anisotropy can lead to chaotic singlepartiele motion and enormous halo formation due tomismatch, which is absolutely unwanted for a high intensityinjector linac .
High Energy Transfer Line between Linac and Accumulator
The transfer line from the
linac to the circular ringsdiffers in some respect from the transfer line between a high
intensity H4' linac and an ADS target station . In both linesthe linac beam is not kept bunched . Space charge forces aresmall but still effective, especially in the longitudinal planeresulting in an increase of the energy spread . The influenceof a conducting pipe has to be considered as the bunchlength is equal or larger than the pipe radius . / 7 /For loss free ring injection into a circular machine theenergy spread of the linac bunches has to be reduced byplacing a bunch rotator at same distance behind the linac.Uncorrelated R.F amplitude and phase errors of :El % resp.±1° will cause at the linac end a beam centre rms energyshift larger than the bunch rms energy spread.In Fig . 4 the longitudinal phase space projections are shownalong the transfer line between the ESS linac and theaccumulator ring . The beam centre at 1 .334 GeV outputenergy is shifted by 3 MeV due to accumulated RFamplitude and phase errors . As pointed out before, RF fielderrors lead to phase space filamentation by exciting acombination of the high and Iow mismatched envelopemodes . In Fig 4, phase space filamentation is caused byexciting a pure 20 % transverse and 20 % longitudinal highmode at 70 MeV CCL input.The ferst row of Fig . 4 is showing the by 3 MeV shiftedlinac output distribution and the corresponding one at theentrance of the bunch rotation cavity after 70 m with a puresinusoidal RF field . The second row is showing the phasespace distribution directly after the bunch rotator and 65 mafterwards at ring injection. The beam is transversely keptfocussed.Clearly visible is the energy spread reduction from 6 MeVat the bunch rotation cavity entrance to about 2 MeV at theexit of the bunch rotation cavity . All particles are now wellinside the ± 2 MeV energy spread Limit for lass free ringinjection . After bunch rotation, the by 20° in phase shifteddistribution of Fig. 4 looks sirrülar to the not shown case fora matched beam at 70 MeV CCL input.
Fig . 4 : Phase space projections at the linac end, before andafter the bunch rotator, and at ring injection . A 20 % highmode is excited at 70 MeV . The beam is shifted by 3 MeVat the linac end.
Placing the bunch rotator before an achromatic cleanupsection, which can require a Jong straight line, results in a'seif-adjusted' system for simultaneous correction of the
-20
0
20
Phase (deg)
186
energy steift and reduction of the energy spread . After bunch
rotation there should be typically less than 10- 3 prüdesoutside ±10-3 in momentum spread . Shortening the straightline by placing the bunch rotator alter the achromaticcollimation section needs a sophisticated adjustment ofmore than 2 bunch rotators . / 8 /
REI-ERENCES1
A. V. Fedotov, R . L. Gluckstern, Preie . PAC 99,New York, USA, p . 606
2
A. Letchford et al, Proc . PAC 99, New York,USA, p. 1846
I . S. Gardner et al, Revised Design for the ESSLinac,
ESS report 99-94-A, Aug 1999
4
K. Bongardt et ah, High Intensity H- InjectorLinacs, ESS report 99-100-L, Nov 1999
5
"The European Spallation Source ESS Study",Vol . 1 to 3, March 1997
6
L S. K. Gardner et al, Proc . PAC 97, Vancouver,Canada, p . 988
7
K. Bongardt et al, Proc . EPAC 96, Sitges, Spain,p . 1224
D. Raparia et al ., Proc . LINAC 98, Chicago, USA,p . 818
9 M. Palast, K . Bongardt, Analytical Approximationof the Three Mismatched Bunched Beam Modes,ESS report 97-85-L, August 1997
for the high and Iow mode which couple the transverse andlongitudinal directions. The modes frequencies areexpressed by the full and zero current transverse andlongitudinal tunes ot , o-to,and mo.
For the quadrupolar mode one has for the relativemismatched amplitude ratlos
AayAa x _
ay ,
Here only anti-phase transverse rnismatches is present . Incase of the high and Iow mode one has
Aa Aa
Abg
(1,0ayo
are -bo
gH is always positive and gL always negative.
The analytical expressions are derived for a uniformfocusing channel with linear external and space Chargeforces . The derivatives of the form-factors are neglected.Numerical simulations of a periodic bunched beamIransport line with spherical bunches (b/a - 1) or elongatedbunches - 3) have shown that all three eigenmodes canbe excited by using the above stated amplitude ratios.
Due to non-linear space Charge forces, particles have tunesdistributed between the full current and zero current tune.The condition for exciting a parametric resonance eithertransversely or longitudinally is given by
2
2)Cr env,HlL -2(cr to -,
with2
2ffto -
arrL=
-ff t
ajP1 m
1
1 : Institut für Schicht-und Ionentechnik ISI2 : Rutherford Appleton Laboratory, U .K .
with
.2--ö- en,
n
=
2> 3'
APPENDIX : Parametric Parade - Envelope Resonance �
uw
For realistic particle distributions, with non-linear spaceCharge forces, partieles inside the beam core have differenttunes . Parametric particle
envelope resonances can occurbetween the single particle tune and the frequency of the
P
where 0-env is one of the three mismatch envelope tunes and
mismatch of the oscillating beam core.For a bunched beam the frequencies of the three mismatcheigenmodes are approximately given by / 9
dPt
is the single particle tune .
di en, = 2o-
for the pure transverse quadrupolar mode and by
ffenv,H = A+% ffenv,L - A -Bwith
co°2
3 2
22 .
2
1
2
3
2
2
2
2
2o-, -
2-oh° -
2-oh + 2(aw -ruf )(ah,-
2
and
187
Puls ed Mode Operation of the FZJ 500 MHz sc Cavity Teststand
K. Bongardt
ABSTRACTAn attractive option for the high energy paff of the pulsed5 MW ESS injector linac is to use 700 MHz super-conducting (sc) multi cell elliptical cavities from 100 MeVon. Lass free ring injection requires better than ± 1% resp.± 1' RF amplitude and phase stability during the 1 .2 mseclang ESS beam pulse. The 50 Hz ESS rep .rate leads toremaining cavity wall deformation from pulse to pulse.Multi cell modes are strongly excited for the ESS sc cavitiesbelow 200 MeV proton energy.An experimental program is outlined for the FZJ scteststand with its 500 MHz, ß = 0 .75 elliptical cavity and its20 kW peak RF power unit . The goal is to study with atleast 5 MVlm accelerating gradient the excitation of multi-cell modes up to 100 Hz rep .rate. The aim is to keep RFamplitude resp . phase oscillations below ± 1 % resp . ± 1'during each individual 1 .2 msec flattop pulse with only 20% increase of the nominal RF power here . Depending onthe experimental set up, multi cell modes can weakly orstrongly excited.Due to the 20 kW peak RF power limitation, the FZJ scteststand will either overstress or understress the situation ofthe 700 MHz ESS sc linac.
Lorentz Force Detuning for pulsed sc Proton Linacs at highrep. rateSuperconducting cells are a very interesting option for thepulsed high ß proton linac . In order to accelerate at 100 Hzrep. rate a proton beam from 100 MeV on various technicaland physical difficulties have to be overcome which are notexisting for the acceleration of pulsed electron beams.
Loss free injection into the 5 MW ESS compressor ringsrequires uncorrelated RF amplitude and phase errors ofeach individual CCL or multicell sc cavity to be smallerthan ± 1% resp . ± 1' . Otherwise the resulting shift of thebeam centre in energy and phase at the linac end are toolarge for being corrected by the bunch rotator . 1RF amplitude and phase errors for a pulsed sc cavity arecaused by Lorentz force frequency detuning and/or micro-phonics noise . Their relative importance is different for sccavities fabricated in bulk Niobium or Niobium sputteredon copper . 1 /
Lorentz force detuning means a decrease of the cavity fre-quency due to wall deformation caused by the acceleratingfield. The frequency change is described by a first orderdifferential equation with 2 constants : the frequencydetuning km and the time constant t m / 2 / For sc cavities
fabricated in bulk Niobium tm values about 1 msec are re-
ported. As a consequence, the cavity frequency is changingduring the filling process and flattop.
The calculated frequency detuning km is shown in Fig . 1 for
600 MHz JAERI-NSP / 3 / bulk Niobium cavities as afunction of ß . Even for stiffened cavities at ß=0 .5,corresponding to about 100 MeV proton energy, thefrequency detuning value is one order of magnitude higheras for the ß=l, 1 .3 GHz Tesla Test Facilty TTF cavity.Limiting the accelerating gradient here is the consequence .
Lorentz Detuning Constant, km , of NSP SC cavitiesC ENS/JAER1
.efe paa-dip=
4-i5
, -45
-00-a,
0.441 0,45 0 .50
0 .60 065 0.70 0 .75
0.R5 0.90 0.45
Frequency 600 MHz
Thickness : 3nvn
Fig . 1 : Frequency detuning km as a function of ß (courtesy
of the JAERI proton linac group)
Fig . 2 shows the caIculation of the time dependent walldeformation for the ß = 0 .604, 600 MHz JAERI-NSP bulkNiobium cavity. The assumed accelerating gradient of 4 .8MV/m is reached after 1 msec filling time. The corres-ponding asymptotic Lorentz force frequency detuning is-175 Hz. The numerical by multicell mode analysis
obtained frequency detuning at the end of the 2 msec Iringbeam pulse is by -33 Hz smaller than the asymptotic singlecell value . Wall deformations are still visible 5 msec afterturning off die RF input power . Without microphonics noisea steady state condition is reached after saure time, beingidentical from pulse to pulse even for 100 Hz rep . rate.
C EN ER .reire om6zn nokok mim.
Cavity deformation & detuning on pulsed aperation(Axial doplocoimpf of mode 8222, frequency ehanue)
Fig . 2 : Time dependent wall deformation for an unstiffened600 MHz, 3 mm wall thickness cavity (courtesy of theJAERI proton linac group)
With microphonics noise as large as ± 30 Hz die situation ismuch more complicated . Measurements of the T 1 1-1 .3 GHz cavities at rep . rates below 10 Hz with 15 MV/mgradient in a single pulsed mode and by applying digitalfeedback systems / 4 have demonstrated excellentamplitude and phase stability for the vector sum . Howeverfor the 8 individual cavities connected to one RF unit, here
10 % resp . ± 10° fluctuations are obtained due to micro-
a2. OrdmilIrdm . . . /IM•12MIOOI133dIE2O1III1B1M111313ffl121RIC1111WZMMMOMIIIIffllll»i
11O2I1IMM0IIIII1M1I1R1M1H1II»WilIllIO1BEIfflUSS3I1B8IMIR
188
phonics noise and different cavity performances underLorentz force detuning . / 5 /The single pulse amplitude and phase behaviour is excellenteven for gradients larger than 20 MV/m if one cavityconnected to a RF unit.
Medium ß=0.5 cavities for at 100 Hz pulsed proton linacsshould be connected to their own RF unit only . The highrep . rate leads to remaining cavity wall deformation frompulse to pulse . Controlling the vector sum, adequate forrelativistic electron Ihmes, is not sufficient to guarantee lossfree ring injection . Beam signals / 6 / can be used asadditional information later on but probably not during thestart-up period. Inter-cell stiffeners are necessary forreducing Lorentz force detuning, to get resistance againstvacuum load and to increase the mechanical resonancefrequency above 100 Hz. / 3, 7 /
Parameters for the 700 MHz ESS sc High Enerey LinacAn attractive Option for reducing length and operating costsof the ESS injector linac with its 64 mA pulse current is touse 700 MHz sc multicell elliptical cavities from 100 MeVon.For assumed 5 MV/m gradient in a ß 0 .45 bulk Niobiumsc cavity with about 2 % cell to cell coupling / 8 1, usefularound 100 MeV proton energy, the matched 3 db band-width is ± 1180 Hz . A large cell to cell coupling isnecessary to achieve better than ± 1% field flatness in a 5cell cavity with its required 100 kW beam power . For a by asingle ring or alternatively by plasma spraying / 9 / stiffenedcavity, the expected Lorentz force frequency detuning isabout - 625 Hz, see Fig 1 . Higher accelerating gradients arenot useful due to overloading the RF control system andexciting a longitudinal 90° partiele lattice resonance . 1 /For assumed 10 MV/rn gradient in a stiffened ß = 0 .6 sccavity with 2 % cell to cell coupling / 8 0, useful around 200MeV proton energy, the matched 3 dB bandwidth is ± 700Hz, compared to expected - 300 Hz Lorentz force frequencydetuning, see Fig 1.The filling time for both cases is about 0 .2 msec . The cavityfrequency is decreasing during flattop for both cases . Inaddition multicell modes are strongly excited, see Fig 2 . Forproton energies well above 350 MeV, Lorentz force fre-quency detuning and multi cell mode excitation are muchless pronounced.
Experimental Program for the FZJ 500 z sie TeststandThe unstiffened ß = 0.75, 500 MHz sc bulk Niobium cavity,built by ACCEL Instruments, is expected to reach 10 MV/m
gradient with at least Q0 = 1*Io9 after high power RF pro-
cessing . The First mechanical resonance is above 50 Hz./ 10 / The Lorentz force frequency detuning value is
-2 Hz/ /m)2 for the 3 .8 mm cavity wall thickness . 11 /The goal of the experimental testprogram is to study with atleast 5 MV/m accelerating gradient the excitation ofmulticell modes up to 100 Hz rep .rate, see Fig 2 . The aim isto keep RF amplitude resp . phase oscillations below ± 1%resp. ± 1° during each individual 1 .2 msec flattop pulse withonly 20 % increase of the nominal RF power here.In Fig 3, the resulting gradient in a pulsed mode for the FZ .J500 MHz cavity is shown by choosing ± 250 Hz cavitybandwidth, leading asymptotically to only 4 .46 MV/mgradient due to the 20 kW RF power limitation. Theexpected Lorentz force frequency detuning is - 10 Hz for
the 2 .23 MV/m chosen gradient at flattop with its 5 kWnominal RF Power. These experimental conditions areintended for testing and optimising the digital RF controlsystem. Indication of multi cell mode excitation can beobtained by operating at 4 MV/m flattop gradient, reachedafter 1 .6 msec and requiring 16 kW nominal RF power.
SC Cavity Teststand at FZ Jülich(500 MHz, 20kW RF powe); 01= 10'
+1- 250 Hz
6
2
4time im]
Fig . 3 : Filling process for the FZI-cavity, large bandwidth
In Fig 4, the resulting pulsed mode gradient for the FZJ 500MHz cavity is shown by choosing ± 50 Hz cavity band-width, leading asymptotically to 10 MV/m gradient . Theexpected Lorentz force frequency detuning is - 50 Hz forthe 5 MV/m chosen gradient at flattop with its 5 kWnominal RF power . Moderate excitation of multi cell modesis expected . Operation at 8 MV/m flattop gradient, reachedafter 5 msec and requiring 13 kW nominal RF power, willresult in quite pronounced multi cell mode excitation.
The experimental conditions in Fig 4 are somewhatdifferent than for the ESS sc linac below 200 MeV, wherethe Lorentz force frequency detuning is only half of thematched ± 3 dB cavity bandwidth but with pronouncedmulti cell mode excitation at flattop. If each sc cavity isconnected to its own RF power unit, then the layout of thedigital RF feedback control loop is easier for the ESS firmethan for the FZJ teststand cavity due to the larger ESScavity bandwidth . Therefore the experimental teststandconditions in Fig 4 are overstressing the situation of theESS 1inac.
Fig . Filling process for the I-ZJ-cavity, small bandwidth
A more realistic teststand situation with greater than± 100 Hz 3 dB cavity bandwidth and still 5 MV/m gradientat flattop requires more than 40 kW peak RF power.
Enlarging the 500 MHz cavity bandwidth to ± 100 Hz withthe available 20 kW RF power, results in reaching 5 MV/mgradient after 2 .5 msec filling time and approaching7 MV/m gradient asymptotically . The nominal flattoppower is 10 kW now. Moderate excitation of multi cellmodes is expected . These experimental conditions areunderstressing the situation of the ESS linac.
SC Cavity Teststand at FZ JülichHz 20kRF power) ; = *10' -> f„~ _+!- 50 Hz
0
189
ACKNOWLEDEMENTSGratefully acknowledged is the exchange of ideas withmang different persons and institutions. Special thanks aregoing to the JAERI proton linac group, to M. Pekeler,former TTF group member, now at ACCEL Instruments,and to T . Schilcher, former TTF group member, now at PSIZürich . The continuous support of M. Pabst, R . Tülle andA. Schnase in writing this report is more than appreciated.
REBERENCES
1 K. Bongardt, M . Pabst, A. Letchford, High Intensity H -Injector Linacs, ESS report 99-100-L, Nov 1999
2 A. Mosnier, Dynamic Measurement of the LorentzForce an a MASCE Cavity . TESLA report 93-09, 1993
N. Ouchi et al, Proton Linac Activities at JAERI,Particle Accelerators, Vol . 62, 1998, p . 17
4 S.N. Simrock et al, Proc . EPAC '96, Sitges, Spain,p . 349
5 T. Schilcher, Vector Sum Control of PulsedAccelerating Fields in Lorentz Force DetunedSuperconducting Cavities, TESLA report 98-20, 1998
6 M. Hüning et al, Proc . LINAC `98, Chicago, USA,p.543
7 D.L. Schrage, E . Swenson, Structural Analysis of APTSuperconducting Cavities, Los Alamos reportLA-UR-93-3151, 1995
8 B. Aminov et al, Conceptual Design of theSuperconducting High Energy Linac for die EuropeanSpallation Source ESS, ESS report 96-60-L, Dec 1996
9 S . Bousson et al, Proc. PAC "99, New York, USA,p .919
10 W. Diete et al, Proc . PAC '99, New York, USA, p . 957
11 the Finite Element Analysis was done by D .L. Schrage,Los Alamos National Laboratory
190
Te h
elr_
r
11 . DATA ACOUISITION, ELECTRONICS,IICONDUCTOR DETECTORS,1uh ETS
192
11 . DATA ACOUISIT ON, ELECTR . im
SEN k,0 ADUC
DE m E(...,TTARGETS
194
Semiconductdr Deteetors and Targets
G. Fiori, A. Hamacher, T. Krings, H . Metz, J . Pfeiffer, D . ProtfC
One of the main activities in the laboratory was connectedwith the preparation of the detector system "GermaniumWall" for GEM-experiments at COSY [1], as well as itsmounting and maintenance at the experimental place . Afterdie last experiment in October 1998 the Quirl-detector andthe larger E-detector could be recovered from radiationdamage by langer heating at 380 K inside the cryostat . Thesmaller Esdeteetor, made from p-type germanium, could notbe regenerated by this relatively simple procedure . Evenafter the detector was removed from die holder andarmealed in oven at 470 K the charge collection was still tobad for further use . A new E-detector of the same size hasbeen produced from n-type gerrnaniurn . The tworegenerated detectors and the new one were successfullyused as "Germanium Wall" during die GEM-experiment inManch 1999 . As both E-detectors were made from n-typegermanium and were not seriously hiradiated a goodrecovery could be perforrned after the beam time by heatingat 380 K inside the cryostat.
A lengthy series of experiments has been undertaleen toestablish a manufacturing process for implanted detectors inwhich originally n-type germanium does not change into p-type . Although certain correlations between the surfacepreparation, implanted ion-dose and annealing parametershave still not been completely understood several - 15 mmthick n-type diodes could be manufactured . One of them hasthen been prepared as die second &deteetat- of the"Germanium Wall" . This detector system will now becompleted for the firnt time, containing one Quirl-detectorand three n-type E-detectors . Further efforts are still neededto irnprove the quality of the implanted nf-contact,especially conceming the small leakage eurrents.
Various position sensitive Si(Li)-detectors with boron-irnplanted contact were produced from 4 to 6 mm thicklithium compensated silicon for ANKE-experiments and fordie diagnosis of the exte COSY-beam. Two detectorswith 80 strips on an area of 20x10 mm 2 were prepared toreplace die already used one, which has indicated veryserious radiation damage after the ferst use at ANKE . Oneof them was installed at ANKE as die E-detector of aspectator-telescope and tested during die experiment inApril 1999 [2] . To enlarge the acceptance of the telescopetwo position sensitive detectors have been manufacturedfrom a 5 .5 rnm dick silicon slice of 3 inch diameter . Eachdetector has been equipped with 200 strips on the boron-irnplanted contact, with a pitch of 234 Inn. The resultingsensitive area arnounted to 11 cm 2 (4 .68x2.34 and thesensitive thickness about 4 .6 mm. One detector has beenplaced in a holder with a miniaturized resistor chain an aceramic board . All strips have been connected to theresistor chain by bonded aluminiurn vvires . This detectorwas used as the E-detector of the spectator-telescope duringthe ANKE-experiment in September 1999 . By means ofsuitable read-out it was possible to identify differentpartieles and to measure their energy and position; this infour neighbouring sectors, each defmed by 50 strips .
Although the reverse current of the detector wassignifieantly increasing during the be -time it wasproperly working up to the end of the experiment . °s timethe radiation damage was not so severe as after the forrnerexperiments . The second detector will be mounted and usedin next experiments.
Thorough laboratory tests confirm that new Si(Li)-detectorsshow stable reverse current and position resolution derivedby read-out through a resistor chain, independently of theenvimnment (air or vacuum) . But seriously increasingreverse currents, sometimes up to more than order ofmagnitude, could be observed at both Si(Li)- and HPGe-detectors if they had uncovered quard-ring surfaces inside abeam line . Fortunately, the electrical resistance between theguard-ring and the elements of the position sensitivestructure remained as a rule high enough to prevent adeterioration of the position information due to evidentlyhigh current through the guard-ring . This excessive currentis probably generated either through impinging protons orhydrogen (H or H 2 ) or certain sputtered material reu hingthe open surfaces of the guard-ring . Several treatments toavoid this troublesome current have been initiated, likepassivation of the guard-ring by evaporated SiO-layers,exposing to 0 2 -plasma or placing into a properly shieldedholder. Another problem, which can be neglected at Si(Li)strip detectors with read-out through a resistor chain,isslowly decreasing resistance between the position elementsduring measurements in vacuum. But for die plarmed read-out of diese detectors by means of chip-electronics such abehaviour could seriously affect die energy resolution ofindividual strips . Some passivation procedures will beneeded to reduce the vacuum dependence of die resistencebetween the strips.
The collaboration with the University of Stockholm (0°-spectrometer) has been successfully continued. Before thelast experiment inside the CELSIUS-ring the xy-positionsensitive germanium detector had to be repaired sinne dieholder and several bonded wires had been darnaged at theexperimental place.For the new collaboration with GSI-Darmstadt a 200 stripgermanium detector, together with preamplifiers mountedaround, has been finished [3].
Different targets were produced for IKP-gmups, arnongthem also Erl70 for the GASP-collaboration and uranium oncarbon backing for COSY-13 . A technician from theCOSY-group was trained in procedures needed atproduction of thin carbon targets for COSY injectionsystem. Diverse metallic layers were evaporated (T0F--deteetors) and special cleaning procedures performed .ManyIKP-groups were supported in solving diverse lab problems.
Referenees:[1]GEM-Collaboration, this Annual R[2] ANKE-Collaboration, this Annual Report[3]200-strip germanium detector for x-ray spectroscopy at
the ESR storage-ring, this Annual Report
195
200-Strip Germanium Detector for x-Ray Speetroshopy at the ESR Storage Ring
D.Protic, T .Stöhlker* , J .Bojowald, G .Borchert, G .Fiori, KIlamacher, H .J .Kluge * ,
C .Kozhuharov * , T.Iüings, H .Metz, I .Mohos
. GSI-Darmstadt, Gerrnany
For the eurrent x-ray spectroscopy at the ESR storage lang(GSI-Darmstadt) a position sensitive germanium detectorfor the hard x-ray regime (10 to 100 keV) has beendeveloped mainly by the Semiconductor Detector Group [1]in collaboration with Atomic Physics Group at GSI-Darmstadt . The general features of such detector systemsare, besides their position sensitivity, a good energyresolution along with timing capability [2] . These propertiesmake such a detector System also very well suited to fulfillthe requirements of the erystalsspectrometer project.Furthermore, a broad range of new challenging experimentscan be anticipated, e .g. precise lifetime and Doppler tunedexperiments.
At the beginning a 4 .1 nun thick germanium diode wasproduced with boron implanted front contact and about0.6 mm thick Li-diffilsed rear contact . The positionsensitive stmaure of the detector has been realized by anarray of 200 strips, each of them 200 iam wide and 23 .4 mmJong, separated by 35 [am wide grooves etched through theboron implanted contact. This means that the positioninformation can be obtained from an area of 47 x 23 .4 mm2(1100 mm2) . A guardsring which surrounds this areaenables also relatively simple assembling . Each strip hasbeen joined to a prearnplifier placed outside of the cryostatwith printed leads inside the flexible Kaptonsfoil (Fig . 1).All cormeetions between the strips and printed leads havebeen performed through bonded Al-wires . The Kaptonsfoil
pressed between two Vitonsseals serves at the same time asvacuum feedthmugh. A 2 lIs Vahian ion-pump maintains thepressure inside the cryostat below 5x 10 -7 mbar.
Thorough laboratory tests were performed using 24 'Am Ihrays . A lot of effort is needed to avoid deterioration of thespectra caused by ground loops, microphonics, differentpicksups and high-frequency oseillations . By properreducing of such effects the energy resolutions of the stripswere found to be in the range of 1 .6 to 1 .9 keV [FWHM] for60 keV ysrays using a commercial shaping amplifier with6 ps time constant . The main contributions to theseresolution figures, as experimentally determined testing thesystem without germanium detector, are caused by Kapton-fall itself (inter-lead capacitance and dielearie lass effects)and its capacity to the grounded cryostat . Only slightlyimproved resolutions could be obtained by very carefullayout of the connection elements (Kapton-foil and vacuumfeedthrough), especially for higher nurnteer of stripelements . Simultaneously with measuring the signals fromthe strips there is possible to process the signals obtainedfrom the comrnon rear contact . The measured energyresolution amounted to about 4 keV [FWHM] . Betterresolutions (< 2 keV) would be achieved by placing the ferststage of the preamplifier inside the cryostat, near to the rearcontact.
A two-dimensional (25 x 160 orthogonal strips) gerrnaniumdetector system is being under development.
Fi .
e main part of the detector Systemwithout the cryostat-cap and thecover for the electronics . 200commercially available Iowdissipation (50 mW) eharge sensitivepreamplifiers (CSPA 02 .04 frorrh
KI-Budapest) are placed an botfhsides of the printed board outside the lcryostat . 100 of them are visible
e picture . The octagonal housing'i fr the preamplifiers has a diameterof 39 cm and 12 cm in depth . Noventilation of the housing is neededsince the total thermal dissipation (in
preamplifiers amounts to onk10 W. The consumption of nahenitrogen amounts to - 3 Fday.
1]Semiconductor Deteetors andTargets, this Annual Report
2] G.Rossi et al ., Nucl . Instr . Mett ,.A 391 (1997) 264
COSY Experiment Data Acquisition and Proeessing
K.H. Watzlawik, M . Karnadi
In collaboration with institutes inside the Elduelieh andother research centers the activities due to the advancementof COSY experiments have been proceeded /1,2/ . The maintopics in this intention are the cooperation with physicists inthe realization of experiments at COSY as well as the pro-viding of the data processing processing infrastmaure.
At experiments, the buildup of data acquisition will be sup-ported in the installation of various systems . These are inparticular systems based on CAMAC, FASTBUS andVME, equipped with Motorola CPUs running the OS9operating system and such as, based on Intel PCs using theNetBSD operating system. Therefore the installation andhandling of Instrumentation Systems and different CAMACand FASTBUS modules including the frontend CPUs,VICbus interfacing and networking will be provided.
At COSY-11 experiment, the substitution of the MotorolaCPUs by Intel PCs is still in progress . The ReadOutCon-trollers (ROCs) are realized by PCs using Interface cards toCAMAC or FASTBUS . SubeventReaders (SERs) and theEventbuilder (EB) are replaced by PCs acting as EventManagers . Vize the VICbus for intercrateconnections andEthernet for slow control, by this implementation for both,the slow control and the event data Ethernet are used. Sub-sequently, the experiment control system "Wendy" /3/ willbe extended regarding the EMS features related to the newfrontend architectu.re.For the development of data acquisition a system was putinto operation, consisting of two ROCs (one CAIVIAC andone FASTBUS) and one Event Manager.As requested, for the Multipurpose Instrumentation Sys-tems, an Initialize function was implemented in Wendy.This function aliows among others the reset of diversehardware at start of a new run according to user program-mahle command List.
For the ANKE experiment, on about 25 PCs the operatingsystem SuseLinux pers . 6.0 or 6 .1 were talled or up-graded. The experiment control and data analysis softwareespecially EMS, CERNlib, XD-sorter base software and theGEM-Lib have been implemented under True64 Unix andthe actuai Linux distribution.To distribute experiment data inside the collaboration, aLinux PC equipped with two DLT and one Exabyte tapedrives has been established as a tape copy station.
The providing of a data processing strueture for COSYexperiments comprises the buildup of the central Unixserver and workstation groups as well as the sustaining ofresources for the data acquisiton at experiments and for theanalysis of experiment data . In operating systems, support isgranted for DigitalUnihe, ULTRIX, Linux, NetBSD andOS9. Accordingly, the instruction of users is provided in thehandling of operating systems and the software develop-ment .
At the central Unix server and several Alpha workstationsthe operating system True64 Unix was upgraded to pers.4 .Od. Various software products arranged according to thetopics : data acquisition, data analysis, document prepara-tion, network comrnunieation and software developmentwere implemented or updated.
To prevent longer downtime of the central Unix server inesse of disk failure, for all essential disks, a disk shadowingwas established . Therefore scripts have been programrnedallowing the weekly automated online backup of the sys-temdisk, the disk with user accounts and disks holding thepublic software for the NFS access of all experiment com-puters . Additionally, from the whole filesystem a seifsdingbackup to die tape drive has been performed . In esse of adisk crash the server is rurming with the haft functionalityafter a downtime of a few minutes.
The Clusters for diskless frontend CPUs, the OS9 andNetBSD clusters were extended and continuously supportedfor the C0SY 1 1, GEM, ANKE and LA DA experi-ments.
To achieve a higher degree of functionality at Linux PCs, sofar for Windows existing software packages, the WordPer-fect, StarOffice, Applixware and the Mathematica wereimplemented at Unix Server . For users preferring to nmtemporarily other operating systems, e .g. Windows on theirLinux PC, the server implementation of the VlVlware pack-age is still in progress . By the VMware, at the control ofLinux a virtual machine will be established, allowing toinstall one guest operating system at the virtual disk locatedinside the Linux file system.Besides of Alpha workstations rurming True64 Unix, LinuxPCs with manifoid functionality are now established in thedata processing at experiments.
The activities due to buildup a duster for Linux PCs havebeen continued. Inside the duster, the operating system andall co an software are located on the server. For useraccounts and user data local disks at the clients are used.The access of die clients to the server is provided by S.The design of an appropriate duster file system is still inprogress . Booting of clients halte place by bootfloppy, com-prising the conjugated kemel, or network using a bootrom,which loads the kemel from the server.For booting the PC clients across the network, the Netbootsoftware is used to build the bootrom image and to preparethe kemel . At now, the remote boot of Linux PCs with the100Mbps NetworldnterfaceCards DE500BA and 3C9O5B,equipped with the appropriate EPROM have been testedsudeessfully.
References/1/ IKP Annual Report 1998 (3640) p . 20212/ MP Annual Report 1997 (3505) p . 217/3/ IEEE Transactions on Nuclear Science February 1996,
Vol .43, No.1, p .44
197
Eleeronies
J . Bojovvald, H . Labus, E . Brökel, N. Dolfus, W. Ernst, G . Lürken, and R. Neilen
In the LKP-electronics laboratory activities were carriedout for the COSY-region, here espeeially for thediagnostie instimmentations at COSY and theand for the nmlear experiments with COSY-external experiments at CERN and PSI were s aswell as one technological transfer project . Among themwere developments of electronie systems and devices,which are not commercially available, deetonic supportduring rumning experiments, consultation and assistaneefor physieists, and common serviees like repairs,purehase and storage of electronie devices andcomponents . Same of the developrnents were carried outin cooperation with the COSY-diagnostic group. Theprojeetirtg activity for the new ATM-computer networkperforaied in cooperation with ZAM and ZEL wasconcluded and the installation started. In the followeig therepresentatiw activities are listed and briefly deseribed.
Activities for COSY:A detector based on special data processing from photomultiplier signals has been developed and is now tested.lt allows absolute intensity measurements of extracted
s within a wide range of intensity and energy ascalibration can be performed on live for each type ofpattkies and energy. lt can be used from some lo3 Hz to10 12 Hz at stochastic extraetion and even for absoluteparticle cmnfing of pulses from kieker extraetitan whererates of 10u/us can occur . e detector fits into a steelpot of at least 92tnm inner diameter conneeted to anCF100 cylinder via a bellow and be movedpneumatically to and from the measurement positionwithin <5s. The firnt signal conditioning is done in a Idealpreamplifier, DAC- t . ds and a Ioeal controllen Rawdata are then transmitted via a serial RS-485 bus to a PCwhere a live display and control developed withLABVIEW 5 .1 . will cornplete the system.The design of the new Schottky-piekup with devidedelectrodes was completed and the construetion started.This monitor will make possible the Schottky-noisemeasurement in horizontal or vertieal plane, respeetively,after proper combination of the part-electrodes by coax-relays . In order to rereive a high sensitivity the electrodeswill totally surround the beam . The monitor will be usedas electrostatic pickup with high im . ce preamplifiers,therefore a flat frequency range of 0 .1 -- 70 MHz willInsult The sensitivity will be further enhanced byresonant tuning of the electrodes.A method for determination of the particle numher inCOSY from the broad-band BPM-sumsignal wasdeveloped and realized . lt was designed in addition to thetwo methodes for particle detefmination already atCOSY, namely from the BCT-signal arid the narrow-bandBPM--sumsignal,
,use these have in some easesdisadvantages which deteriorate the accuracy.The wall current monitor (WCM) was installed in theextraetitan mahne to the ESS-experiment JESSICA . ltwill be used for measurements of pw.fiele number andtime structure of fast extraeted proton-bunehes . First
experiments at 180 MeV proton energy showed thesmeessüd operatkm of the WCM in this application:single proton hmeheia with 2-10 7 protons per tameh andca. 200 ns width could elearly be registered and evaluated.
Activities for the expetiments:The production of the eleetronie moduls and trat es for theextension of the signal eharmels (ca . 400) at ANKE wasgarrad, which are n wt,i ed for the K-detector system andwork successfully in the present ANKE-electronics setup.These are mainly the analog-fanout moduls with settable(by jumper) gain and the cable-adapter moduls to matchthe thick and solid, laut Iow-Ions (needed because of 60mlength) coax- and tvvinax-eables to the flexible multi-coaxcables with speeial multi-pin conneetors, which join theconnectors at the modules of the experiment electronics.The signal processing electronics of AT . i was built up(400 channels) and successfully tested . Otte to lack ofspace in the detector region a compact electronics wasdesigned with multi-layer boards and S -components.The electronics contains preamplifier, discriminator withremote settable threshold and pulse stretcher for eachchannel, and analog-sum- and multiplieity-outputsrammen for 16 channels . In order to reduce crosstalkbetween channels the interconnections were made withstriplines (on boards) and multi-coax cables . The observedcrosstalk is less than 2% during the rise and fall times ofthe pulses . For overload-protection of the photomultipliersduring the .- .ii injeetion interval the multiplier high-voltages are reduced by TTL-control signal for 350V or600V, respectively. The switching times are in the ms-region. Together with the signal analyzing electronics(with RAL 111 -chip) and the evaluation program, realizedby ZEL, the total ATRAP experünent electronics wassuccessfully set into Operation.The control of the liquid hydrogen target of the TOF andBIG KARL experiments have been equipped with a newhardware to replace the old PC-DAC-boards and theanalogae interface by a modern field hus system vvhichhas great advantages within !arge experimental areas withdistributed sensors and actors. We choose the FIELDPOINT system from NATIONAL INSTRUMENTS tooptimise the soffware support and efforts to adapt theexisting LABVIEW so are.The control of the erystal o has expandedby several temperature and position sensors as well as anew m' or adjustment. Also in this case the formercontrol via PC-DAC-boards was replaced in parts by theFIELD POINT system from NATIONALINSTRUMENTS . The existing LABVIEW control wasmodified to meet the new demands.Within a Teelmol Transfer Contract a Compton hachsoatter detector was developed which can be used tomeasure the weight per tmit area on litte during tlproduetion of special papers . The detector is able toproe-ess very high raunt rates for high resolution and/orfast measurements. The same detector was alsosuccessfully tested with beta transmission measurements.
198
Vl .
Sc° Council C0SY-
11 .
2! L
ionsVlll Constimmt.
PublicatIons
OSY
In e o ut ors
200
Vl. SCIENTIFIC COUNCIL COSY
IFF, FZ JülichIndiana University, USAThomas Jefferson Lab., VA, USAINC, FZ JülichUniversity of MainzUniversity of MainzUniversity of BonnState University, New York, USAUniversity of Uppsala, SwedenUniversity of HelsinkiDESY HamburgCERN, Geneva
WL ADVISORY COMMITTEES AT COSY(eleeted members)
dviso I.
Prof. A. BoudardProf. Dr. W. GöddeProf. Dr. E. GrosseProf. Dr . C. GuaraldoProf. Dr. M. HarakehProf. Dr . S . Killlander(Chairman)Prof. Dr . R. LanduaProf. Dr. V. MetagProf. Dr . H.O. MeyerProf. Dr. U. MoselDr. E. RadermacherProf. Dr . K. RithProf. Dr . C. Wilkin
CE Saclay, FranceUniversity of BochumFZ RossendorfINFN Frascati, ItalyKVI Groningen, The NetherlandsUniversity of Uppsala, Sweden
CERN, Geneva, SwitzerlandUniversity of GießenIUCF Bloomington, USAUniversity of GießenCERN, Geneva, SwitzerlandUniversity of ErlangenUniversity College London, England
C
xek
v
o ee zu u
0 S MAC
acine Advisory Committee)Dr. K.W. Baurmann WTA, FZ Jülich Dr. N. Anger( GSI DarmstadtDr. D . GrzonkaProf. Dr . D . Husmarm
, FZ JülichUniversity of Bonn
Prof. Dr. D. Husmann(Chairman)
University of Bonn
Prof. Dr . K. Kilian , FZ Jülich Dr. D. Möhl CERN, GenevaProf. Dr . T. Mayer..Kuc University of Bonn Prof. Dr. G. Mülhaupt ESRF, FranceProf. Dr . R. MaierProf. Dr. U. MoselDl U. PfisterProf. Dr . K. SistemichProf. Dr . J . Speth
, FZ JülichUniversity of GießenBD, FZ Jülich
, FZ Jülich, FZ Jülich
Dr. F. Willeke DESY Hamburg
Prof. Dr . H . StröherProf. Dr . J . TreuschProf. Dr . R. Wagner
FKP, FZ JülichVS, FZ JülichVS, FZ Jülich
.,'-,
(Chairman)201
Prof. Dr. P. BraunsMunzireger
GSI Darmstadt(Chairman)Dr. A. BringerProf. Dr . J . CameronProf. Dr . L. CardmanProf. Dr . H. CoenenProf. Dr . D . DrechselProf. Dr . D . von HarrachProf. Dr . E. HilgerProf. P . PaulDr. D. ReistadProf. Dr . D.O. RiskaDr. D. TrinesDr. H. Wemfinger
202
VIII. COLLAB0 TI NS
C0SY-EDDA-Collaboration*Spokesrnen: J . Bisplinghoff, F . Hinterberger, W . Scobel
R. Gebet R . Maier, D . Prasnhn, P . v. Rossen:Institut ffir Kernphysik, Forschungszentrum Jülich, D-52425 Jülich
M. Altmeier, J. Bisplinghoff, T. Bisse!, M . Busch, R. Daniel, 0 . Diehl, H .J. Engelhardt, J . Ernst, P.D. Eversheim,0. Felden, R. Gross-Hardt, F . Hinterberger, T. Hüskes, R.
R . Maschuw, T. Mayer-Kuekuk, H. Rohdjeß,D. Rosendaal, M. Schulz-Rojahn, V . Schwarz, S . Thomas, HJ . Trelle, M. Walker, E . Weise, R . Ziegler:Institut für Strahlen- und Kernphysik, Universität Bonn
F. Bauer, T . Bisset, R . Bollmann, K . Büßer, F . Dohrmann, J . Flammen M . Gasthuber, L Greiff, A. Gross,K. Hebbel, I . Koch, R . Langkau, T. Lindemann, J. Lindlein, M . Pfuff, B . Sanz,N. Schirm, W. Scabel, S . Steinbeck,A. Wellinghausen, K. Wollen1 . Institut für Experimentalphysik, Universität Hamburg
*supported by BMFT-Verbundforschung; University Program of Forschungszentrum Jülich
GOSY-11 Collaboration*Spokesman: W. Oelert
D. Grzaa, K. Kilian, W. Oelert, G . Schepers, T . Sefzick, S . Sewerin, M . Wolke:Institut für Kernphysik, Forschungszentrum Jülich, D-52425 Jülich
M. Jochmann, M. Köhler, P . Wüstner:Zentralinstitut für Elektronik, Forschungszentrum Jülich, D-52425 Jülich
H.H. Adam, A. Khoukaz, N. Lang, T . Lister, C . Quentmeier, R. Santo:Institut für Kernphysik, Universität Münster
L. Jarczyk, P. Moskal, J. Smyrski, M. Sokolowski, A. Strzalkowslci:Institute of Physics, Jagellonian University, Cracow, Poland
A. Budzanowski : Institute of Nuclear Physics, Cracow, Poland
P. Kowina, M. Siemaszko, W. Zipper: Institute of Physics, Katowice, Poland
J. Balewski, C . Goodman: IUCF Bloomington, Indiana, USA
*supported by BMFT-Verbundforschung; International Bureau of the BMBF, DLR-Bonn;University Program of Forschungszentrum Jülich
COSY-13 Collaboration*Spokesman : B . Kamys
W. Borgs, N. Dolfus, S . Geisler, H .R. Koch, P . Kulessa, R. Maier, H. Ohm, D. Prasulm, U . Rindfleisch,0.W.B. Schult, H. Ströher:Institut für Kernphysik, Forschungszentrum Jülich, D-52425 Jülich
L. Jarczyk, B . Karnys, St. Kistryn, K. Pysz, Z . Rudy, A . Strzalkowski:Institute of Physics, Jagellonian University, Cracow, Poland
W. Cassing : Institut für Theoretische Physik, Universität Gießen
1 . Zychor:Soltan Institute for Nuel . Studies, PL-05400 Swierk
M. Matoba, Y. Uozumi:Dept . of Nuclear Engineering, Kyushu University, Fukuoka 812, Japan
*supported by International Bureau of KfK Karlsruhe ; TEMPUS-Program
203
ANKE* (e-Facility)Spokesman : K. Sistemich
U. Bechstedt, N. Bongers, G. Borchert, W. Borgs, W. Bräutigam, M . Büscher, J . Dietrich, D. Gotta,D. Grzonka, M. Hartmann, V. Hejny, M. Hennebach, H . Junghans, M. Karnadi, H .R. Koch, K. Kruck, H . Labus,I . Lehmann, B . Lorentz, R . Maier, S . Martin, M. Nekipelov, R . Neilen, W. Gelen, Ohm, D . Prasuhn, HJ. Probst,D. Probt', R. Schleichert, H . Schneider, G . Schug, O.W.B. Schult, H . Seyfarth, K. Sistemich, H .J . Stein, H . Ströher,K.-H. Watzlawik:Institut für Kernphysik, Forschungszentrum Jülich, D-52425 Jülich
W. Klein: Institut für Schicht- und Ionentechnik, Forschungszentrum Jülich, D-52425 Jülich
G. Hansen, F. Klehr, H. Stechemesser: Zentralabteilung Allgemeine Technologie, Forschungszentrum Jülich, D-52425 Jülich
R. Baldauf, M . Drochner, W . Erven, H . Kleines, H. Loevenich,J . Sakardi, P. Wüstner, K . Zwoll : Zentrallabor ftirElektronik, Forschungszentrum Jülich, D-52425 Jülich
M. Debowski, N . Langenhagen, H. Müller, B . Prietzschk, B. Rimarzig, Chr. Schneider:Zentralinstitut fiir Kernforschung, Rossendorf, D-01474 Dresden
J. Ernst: Institut Rh: Strahlen- und Kernphysik, Universität Bonn, D-53115 Bonn
N. Koch, S . Lorenz, K . Rith, F . Rathmann, F . Schmidt, E . Steffens:Physikalisches Institut 11, Universität Erlangen-Nürnberg, D-91058 Erlangen
W. Cassing, A. Sibirtsev : Institut
Theoretische Physik, Universität Gießen, D-35392 Gießen
R. Eßer, H . Paetz gen. Schieck : Institut Rh' Kernphysik, Universität Köln, D-50937 Köln
H. Adam, A . KhouIcaz, N . Lang, Thi Lister, C . Quentmeier, R. Santo:Institut für Kernphysik, Universität Münster, D-48149 Münster
L. Jarczyk, B . Kamys, St . Kistryn, P . Kulessa, K. Pysz, Z . Rudy, Smyrski, A. Strzalkowski:Institute of Physics, Jagellonian University, Cracow, Poland
V. Abazov, V. Artemov, A. Churin, S . Dymov, O. Gorchakov, A . Kacharava, N . Kadagidze, V .I . Komarov,V. Kruglov, A. Kulikov, V. Kurbatov, V . Leontiev, G. Macharashvili, S . Merzliakov, A . Petrus, M. Sapozhnikov,E. Strokovsky, Yu. Uzikov, A. Volkov, S. Yaschenko, B . ZalilManov, N . Zhuravlev:Joint Institute of Nuclear Research, Dubna, Russia
S . Trusov, V. Yazkov: Dubna Branch of the Moscow State University, Dubna, Russia
S . Barsov, S . Belostotski, O . Grebenyuk, V . Koptev, A . Kovalov, P. Kravtsov, M . Mikirtichyants, S . Mikirtichyants,V. Nelubin, A. Vassiliev : Petersburg Nuclear Physics Institute, Gatchina, Russia
P . Fedorets, A . Gemsimov, V . Chemetzlcy, M. Chumakov, , V . Goryachev, V . Grishina, L . Kondratyuk,V. Tchernyshev:Institute for Theoretical and Experimental Physics, Moscow, Russia
Ye.S . Golubeva: Institute for Nuclear Research, Russian Academy of Sciences, Moscow, Russia
C. Willdn : Physics Department, Univ. College London, London WCI 6BT
N. Amaglobeli, B . Chiladze, M . Nioradze:High Energy Physics Institute, Thilisi State University, Tbilisi, Georgia
A. Mussgiller: FH München, Fachbereich Elektronik, D-80335 München
1 . Zychor: Soltan Institute for Nuclear Studies, PL-05400 Swierk, Polen
Y. Ponski-Boh: Department of Physics, Kasuga, Bunkyosku, Tokyo, Japan
*supported by Land Nordrhein-Westfalen, BMFT (Verbundforschung; Forschungszentrum, WTZ mit Rußland),1NTAS, Collaborators
204
COSY-GEM-Collaboration*Spokesman: H. Machher
S . Abdel-Samad, J. Bojowald, D . Filges, A. Hamacher, K . Kilian, R . Klein, H . Machner, A . Magiera, R. Maier,D. Protic, P . v. Rossen:Institut für Kernphysik, Forschungszentrum Jülich, D-52425 Jülich
K. Zwoll:Zentralinstitut rur Elektronik, Forschungszentrum Jülich, D-52425 Jülich
J . Ernst, R. Jahn, B . Razen:Institut für Strahlen- und Kernphysik, Universität Bonn
D. Frekers, R. Garske, K. Grewer:Institut für Kernphysik, Universität Münster
P. Hawranek, L . Jarczyk, S . Kistryn, W . Klimala, J . Smyrski, A . Strzalkowski:Jagellonian University, Cracow, Poland
A. Budzanowski, L. Freindl, S . Kliczweski, R. Siudak : Institute of Nuclear Physics, Cracow, Poland
H.S . Plendl: Physics Department, FSU, Tallahassee, Florida, USA
B.J . Lieb: Physics Department, GMU, Fairfax, Virginia, USA
L.C. Liu: LANL, T . Division, Los Alamos, USA
H. Nann: IUCF, Bloomington, Indiana, USA
M.G. Betigeri, A . Chatteijee, B .K. Jain, S .S . Kapoor, B .J . Roy:BARC Trombay, Bombay, India
J . Ilieva, T. Kutsarova, E . Pentchev: Institute of Nuclear Research and Nuclear Energy, Sofia, Bulgaria
S . Förtsch : National Accelerator Centre, Faure, South Africa
D. Kolev . R. Tsenov : Univ. Sofia, Sofia, Bulgaria
G. Martinska, J. Urban, M. Ulicny, Univ . Kosice, Slovalda
*supported by BMFT-Verbundforschung ; University Program of Forschungszen tmm Jülich & DLR, Bonn
205
COSY-TOF Cutlahnration*Coordinator: E . Roderburg
S. Abdel-Samad, U . Bechstedt, D . Filges, R . Geyer, H. H . ek, A. Hassan, D . Hesselbarth, P . Jahn, K . Kilian,R. Klein, H. Machner, S . Mummsla, H.P . Morsch, K. Nünighoff, N. Paul, U. Rindfleisch, E . Roderburg, M . Rogge,M. Schmitz, T. Sefzick, P . Turek:Institut ffir Kernphysik, Forschungszentrum Jülich, D-52425 Jülich
H. Nann: IUCF Bloomington, USA
J. Harrnsen, H . Koch, W. Meyer, G. Reicherz, A. Wilms:Institut für Experimentalphysik, Ruhr-Universität Bochum, D-44780 Bochum
H. Dutz : Physikalisches Institut der Universität Bonn, D-53115 Bonn
K.Th . Brinkmann, H. Freiesleben, B . Jakob, L. Karsch, E . Kuhlmarm,
Lange, Ch . Plettner, M . Richter,P . Schönmeier, M. Schulte-Wissermann, G.J . Sun, M. Würschig-Pörsel:T.U. Dresden, D-01062 Dresden
M. Müller-Veggian: Fachhochschule Jülich
R. Bilger, H . Clement, A. Erhardt, J . Kreß, G.J . Wagner:Physikalisches Institut, Universität Tübingen, D-72076 Tübingen
S. Dshemuchadse, P . Michel, K . Müller, L . Naumarm, A. Schamlott:Institut für Kern- und Hatfronenphysik, FZ Rossendorf, D-01314 Dresden
W. Eyrich, M. Fritsch, J . Hauffe, W. Schroeder, F. Stinzing, M . Wagner, S . Wirth: Physikalisches Institut,Universität Erlangen-Nürnberg, D-91058 Erlangen
A. Filippi, S . Marcello, A . Raimondo : INFN Torino, Italien
P. Zupranski: SINS Warschau
*supported by BMFT-Verbundforschung ; University Program of Forsch ungszentrwn Jülich
COSY-MOMO-Collaboration*Spokesman : R. Jahn
H. Machner, P. v. Rossen, R . Töne : Institut für Kernphysik, Forschungszentrum Jülich, D-52425 Jülich
F. Bellemann, A . Berg, J. Bisplinghoff, G . Bohlscheid, J. Ernst, F . Hinterberger, R. Ibald, R . Jahn, R . Joosten,R. Maschuw, T. Mayer-Kuckuk, G . Mertler, J . Munkel, D . Rasen 1, H. Sc tker:Institut feix Strahlen- und Kernphysik, Universität Bonn
P. v . Neumann-Cosel : Institut für Kernphysik, Technische Hochschule Damstadt
L. Jarczyk, A. Magiera, 1 Smyrski, A. Strzalkowski:Institute for Physics, Jagellonian University, Cracow, Poland
A. Kozela : University of Cracow, Poland
C. Wilkin: University of London, England
*supported by BMFT-Verbundforschung ; University Program of Forschungszentrum Jülich;
206
NESSI Collaboration (European Spallation Source (ESS))Spokesman : U. Jahnke
D. Filges, F . Goldenbaum, R .-D. Neef, K . Nünighoff, N . Paul, H. Sehaal, A . Tietze:Institut für Kernphysik, Forschungszentrum Jülich, D-52425 Jülich
D. Hilscher, U. Jahnke:H
eitner-Tnstitut Berlin, Bereich Festkörperforschung, D-14109 Berlin
J . Galin, A. Letoumeu, B . Lott, A . PeghaireGANIL (IN2P3-CNRS, DSM-CEA), BP 5027, F-14021 Caen-Cedex, France
L. Pienkowski : University of Warsaw, 02-097 Warszawa, Poland
J. Töke, W.U. Schröder: University of Rochester, Rochester, New York 14627, USA
P. Figuera: Instituto Nazionale di Fisica Nucleare, LNS, 1-95123 Catania, Italy
*supported by EU-TMR-Program and Helmholtz Strategie fonds
JESSICA-Collaboration*Spokesman : H. Tietze-Jaensch
B. Alefeld, H . Bamert-Wiemer, H . Conrad, J. Dietrich, D . Filges, F . Goldenbaum, B . Guttek, H. Klein, S . Martin,R.D. Neef, K . Niirrighoff, D. Prasuhn, H . Scbaal, H . Stechemesser, H . Tietze-Jaensch, U. UlimaienInstitut fiir Kernphysik, Forschungszentrum Jülich, D-52425 Jülich
P.K. Job, : Argonne National Laboratory (USA)
B. Haft, W. Nienhaus, E. Schachinger: Techn . Univ. Graz (Austria)
Y. Oyama, N . Watanabe: JAER' (Japan)
M. Furusaka : KEK (Japan)
P . Ferguson, E . Pitcher, G . Russen: Los AI os National Laboratory (USA)
T. Gabriel, T . Lucas : Oak Ridge National Laboratory (USA)
G.S . Bauer, H. Spitzer: Paul Scherrer Institut (Switzerland)
T. Broome, H. Jones : RAL (UK)
Y. Kiyanagi : University of Hokkaido (Japan)
*supported by EU-TMR-Program, Helrnholtz Strategiefonds
207
PISA Collaboration*Spokesman : B . Kamys
D. Filges, F . Goldenbaum, K. Kilian, H . Machner, R.-D. Neef, H . Sc l:Institut für Kernphysik, Forsch un.gszentrwn Jülich, D-52425 Jülich
M. Beyss, H . Ulimaier: Institut für Festkörperforschung, Forschungszentrum Jülich, D-52425 Jülich
A. Heczko, Jarczyk, B. Kamys, St . Kistryn, W . Klimala, A. Magiera, W. Migdal, Z . Rudy, J . Smyrski,A. Strzalkowski:M. Smoluchowski Institute of Physics, Jagellonian University, PL-30059 Kraköw, Poland
A. Budzanowski, M . Kistriyn, St. Kliczewski, K . Pysz, R. Siudak:H. Niewodniczanski Institute of Nuclear Physics, PL-31342 Krakäw, Poland
R. Barna, V. D'Amico, D . De Pasquale, A . halianenDipartimento di Fisisca, Messina University and Instituto Nazionale di Fisisca Nucleare, Sezione di Ca a, GrupoCollegato di Messina, 1-98166 Vill . S . Agata (Messina), Italy
A. Bubak, J. Kisiel, W. Zipper: Institute of Physics, University of Silesia, PL-40007 Katowice, Poland
S. Förtsch, D. Steyn : National Accelerator Centre, PO Box 72, Faure, 7131 South Africa
J . Cugnon: Institut de Physique, Universite de Liege, B-4000 Liege, Belgium
P.L. Biermann: Max-Planck-Institut für Radioastronomie, D-53121 Bonn, Gerrnany
*supported by BMFT-Verbundforschung, EU-TMR-Program
TETHYS-CollabdrationSpokesmen : A. Boudard, D . Filges
D. Filges, F . Goldenbaum, K. Kilian, H. Machner, H.P . Morsch, R .D. Neef, E. Roderburg, H . Sch l:Institut für Kernphysik, Forschungszentrum Jülich, D-52425 Jülich
J. Cugnon : Liege University, Belgium
A. Boudard, J .E. Ducret, R. Legrain, S . Leray, Y. Teuren, C . Volant: DAPNIAISPIIN, CEA Saclay, France
J. Frehaut, X . Ledonx, Y. Patin : DPTAJSPN, CEA Bruyeres-le-Chatel, France
W. Augustyniak, P . Zupranski : University of Warsaw, Poland
G. Alldiazov, A.V. Kravtsov, A. Prokofiev: PNPI Gatchina, Russia
E.A. Strokovsky : JINR Dubna, Russia
208
PROMICE/WASA Collaboration*Spokesmen : B . Höistad and S . Kullander
H. Calen, S . Carius, S . Dahlgren, K. Fransson, L . Gustafsson, S . Häggström, B . Höistad, A. Jansson, T . Johansson,S. Kullander, Moehn, A . Mörtsell, R. Ruber, H. Rubinstein, U. Schuberth:Department of Radiation Sciencves, Uppsala, Sweden
K. Kilian, W. Oelert, T . Sefzick:Institut für Kernphysik, Forschungszentrum Jülich, D-52425 Jülich
Z. Wilhelmi, J . Zlomanezuk:Institute of Experimental Physics, Warsaw, Polarid
Z . Zabierowski:Institute of Nuclear Studies, Lodz, Poland
A. Kupsc, A . Nawmt, J . Stepaniak:Institute for Nuclear Studies, PL-00681 Warsaw, Poland
A. Bondar, A . Chilingarov, P . Gaidarev, G . Kolachov, A . Kuzmin, B. Shwartz, V . Sidorov:Institute of Nuclear Physics, Novosibirsk, Russia
Z . Pawlowski:Institut of Radioelectronies, Warsaw, Poland
D. Bogoslawsky, V . Dunin, B . Morosov, A . Povtorejko, S . Sandukovsky, A . Sulchanov, V . Tilthomirov:Joint Institute for Nuclear Research Dubna, 101000 Moscow, Russia
A. Bolozdynia, A . Martemyanov, V . Sopov, V. Tchernyshev:Institut of Theoretical and Experimental Physics, Moscow, Russia
H. Hirabayashi, A . Yamamoto:National Laboratory for High Energy Physics, Tsukuba, Japan
B. Chemyshev, M. Gornov, Y . Gurov, V. Saveliev, R. Shafigullin:Moscow Engineering Physiccs Institute, Moscow, Russia
C. Ekström, A . Johansson, D . Reistad:The Svedberg Laboratory, Uppsala, Sweden
B. Trostell:The Studsvik Neutron Research Laboratory, Studsvik, Sweden
L. Bergström:Department of Physics, Stockholm University, Sweden
H. Shirnitzu:Department of Physics, Yainagata University Japan
H. Ikegarni, Y . Miztmo:Research Center for Nuclear Physics, Osaka, Japan
209
AD-2 Collaboration (ATRAPSpokesman : G. Gabrielse
G. Gabrielse, T. Roach, J . Estrada, D . Hall, P. Yesley:Department of Physics, Harvard University, Cambridge, MA 02138, USA
H. Kalinowsky: Univ. Bonn, ISKP, D-53115 Bonn
T.W. Hänsch, K. Eikeman, J . Walz : Max-Planck-Institut für Quantenoptik, D-85748 Garching
W. Oelert, D . GrzonIca, G. Schepers, T. Sefzick:Institut für' Kernphysik, Forschungszentrum Jülich, D-52425 Jülich
T. Hijmans : Dept. of Physics, Univ . of Amsterdam, NL-1018 XE, The Netherlands
W.D. Phillips, Std- Rolston : National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
J. Walraverr FOM Institute for Atomic and Molecular Physics, 100 DB Amsterdam, The Netherlands
W. Jhe : Department of Physics, Seoul National University, 151-742 Korea
D. Wineland, J . Bollinger : National Institute of Standards and Technology, Boulder, CO 80303, USA
W. Breunlich: Institute for Medium Energy-Physics of the Austrian Academy of Sciences, A-1090 Wien
*supported by BMFT-Verbundforschung, National Science Foundation (USA)
ZEUS CollaborationSpokesman: R. Klarmer, Deutsches Elektronen-Synchrotron (DESY), D-22603 Hamburg
D. Filges, R.D. Neef:Institut RR Kernphysik, Forschungszentrum Jülich, D-52425 Jülichand 49 national and international institutions
210
EUROBALL-Collaboration
R.M. Lieder: Institut für Kernphysik, Forschungszentrum Jülich, D-52425 Jülich
P. von Brentano: Institut ffir Kernphysik, Universität zu Köln, D-50937 Köln
D. Schwa
Kernphysik Heidelberg, Postfach 103980, D-69029 Heidelberg
J. Gera : GSI Darmstadt, Postfach 110552, D-64291 Darmstadt
H . Hübel : Institut für Kernphysik, Universität Bonn, D-53115 Bonn
K .P . Lieb: H. Physikalisches Institut, Universität Göttingen, D-37073 Göttingen
F. Dönau : Institut für Kern- und Hadronenphysik, Forschungszentrum Rossendorf, D-01314 Rossendorf
L Lisle : Department of Physics, Victoria University of Manchester, Manchester M13 9PL, UK
P. Nolam Department of Physics, Univ. of Liverpool, Liverpool L69 3BX, UK
J. Simpson : Daresbury Laboratory, Warrington WA4 4AD, UK
C. Rossi-Alvarez: Istituto Nazionale di Fisica Nucleare, Padova, 1-35131 Padova, Italy
G. deAngelis : Istituto Nazionale di Fisica Nucleare, Lab . Nazimali di Legnaro, 1-35020 Legnaro, Italy
M. Pignanelli : Istituto Nazionale di Fisica Nucleare, Sezione di Milano, 1-20133 Milano, Italy
P.G. Bizzeti : Istituto Nazionale di Fisica Nucleare, Sezione di Firenze, 1-50125 Firence, Italy
B. Rubio : Instituto de Fisica Corpuscular, ES-46100 Burjassot (Valencia), Spain
C. Fahlander : Department of Physics, University of Lund, S-22362 Lund, Sweden
(5. Skeppstedt : Department of Physics, Chalmers University of Technology Göteborg, S-41296 Göteborg, Sweden
A. Jolmson: Manne Siegbahn Institute of Physics, S-10405 Stockholm, Sweden
J . Nyberg : The Svedberg Laboratory, S-75121 Uppsala, Sweden
B. Herskind : NBI, University of Copenhagen, DK- 1350 Copenhagen, Denmark
H. Sergolle : Institut de Physique Nucleaire, IPN, F-91406 Orsay, France
H. Guerreau : Institut de Physique Nucleaire, GA L, F-14021 Caen, France
F . Heck : Institut de Physique Nucleaire, lReS, F-67037 Strasbourg, France
F. Chemin : Institut de Physique Nucleaire, CENBG Bourdeaux, F-33170 Gradignan, France
F. Hannachi, Institut de Physique Nucleaire, CSNSM, F-91405 Orsay, France
211
212
IX. PERSONNEL
Scientific Staff:
DP P. Achenbach (E2)
Prof. Dr. G. Baur (TH)(a .o . Prof. at the Univ . of Basel)
DP V . Baru (TH)
Dr. U. Bechstedt (LI)
Dr. J . Bojowald (Ec)
Dr. K . Bongardt (LI)
Prof. Dr . G. Borchert (E2)(apl . Prof. at the Univ . of Cologne)
DI W. Bräutigam (LI)
Dipl . W. Brands (EI)until April 30, 1999
Dr . M. Büscher (E2)
Dr . P . Büttiker (TH)
C. Deutsch (LI)since July 1, 1999
Dr. J . Dietrich (LI)
Dr . A. Djaloeis (El)
DP S . Dymov (E2)since September 6, 1999
DP S .M. Abd EI-Samad (El)
DP E. Epelbaum (TH)
Prof. Dr . Ch . Elster (TH)since October 7, 1999
Dr. R . Eßer (E2)
Dr. O. Felden (LI)
DP N . Fettes (TH)
Dr. D. Filges (El)(apl . Prof. at the Univ . of Wuppertal)
DP A. Gasparian (TH)
Dr. W. Gast (EI)
Dr. R . Gebet (LI)
Dr . G. Gellas (TH)since May 27, 1999
Dr. R . Geyer (EI)until May 31, 1999
Prof. A. Gillitzer (El)since Sept. 1, 1999
DP M. Glende (LI)until June 30, 1999
J . Goertz (LI)until April 23, 1999
Dr . F . Goldenbaum (El)
Dr . D . Gotta (E2)
Dr . F. Grürmner (TH)
Dr . D . Grzonka (El)
Dr . J . Haidenbauer (TH)
Dr . C . Hanhart (TH)until January 31, 1999
Dr. M. Hartmann (E2)
V. Hejny (E2)since April 1, 1999
Dr. T . R . Hemmen (TH)
DI K. Henn (LI)
DP M. Hennebach (E2)since November 15, 1999
DP D. Hesselbarth (El)
Dr . P. Jahn (El)until Aug . 31, 1999
DP H. Junghans (E2)
V. Kamerdjiev (LI)since June 14, 1999
Prof. Dr . K . Kilian (El)(Prof. at the Univ . of Bonn)
Dr . V . Klemt (TH)
Dr . H . R . Koch (E2)
Dr . O. Krehl (TH)until December 31, 1999
Prof. Dr . S . Krewald (TH)(apl . Prof. at the Univ . of Bonn)
B . Kubis (TH)since January 15, 1999
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DP P . Kulessa (E2)
H. Krebs (TH)since April 1, 1999
Dr . H. Labus (Ec)
H.-R . Langohr (El)
Dr . H. Lawin (LI)
1 . Lehmann (E2)since February 1, 1999
Dr . A. Lehrach (LI)
Prof. Dr . R .M. Lieder (El)(Prof. at the Univ . of Bonn)
Dr . B . Lorentz (LI)since July 1, 1999
Dr . H. Machner (El)
Prof . Dr . R . Maier (LI)(Prof. at the Univ . of Bonn)
Dr . S . Martin (LI)
DP S . Marwinski (El)
Prof. Dr . Ulf-G . Meißner (TH)(Univ.-Prof. at the Univ . of Bonn)
Dr . W. Melnitchouk (TH)until May 31, 1999
Dipl . S . Menzel (El)since Oct . 1, 1999
DP L . Mihailescu (El)
DP M. Mikirtytchiants (E2)since September 20, 1999
1 . Mohos (LI)
Dr. H.P . Morsch (El)
Dr. Ch . Mosbacher (TH)until March 31, 1999
DP G. Müller (TH)
A. Mussgiller (E2)since March 1, 1999
Dr. R .-D. Neef (EI)
M. Nekipelov (E2)since September 20, 1999
Prof. Dr . N.N. Nikolaev (TH)
DP K. Nünighoff (El)
Prof. Dr . W. Oelert (El)(Priv . Dozent at the Univ . of Bochum)
Dr . H. Ohm (E2)
Dr . J . Oller (TH)since September 1, 1999
DI N. Paul (El)
Dr . D . Prasuhn (LI)
DP D . Protic (Dt)
Dr . Frank Rathmann (E2)
Dr . E . Roderburg (El)
Dr . M. Rogge (El)
Dr . P . von Rossen (LI)
Dr . H . Schaal (El)
Dr. W. Schäfer (TH)
Dr. G. Schepers (El)until Dec . 31, 1999
Dr. R. Schleicher( (E2)
Dr . M. Schmitz (El)until Aug . 31, 1999
Dr . A. Schnase (LI)
DP. A. Schneider (E2)
DI H. Schneider (LI)
S . Schneider (TH)since December 1, 1999
DI G. Schug (LI)
G. Schwiete (TH)since December 1, 1999
Dr . T . Sefzick (El)
DP S . Sewerin (El)(until Sept. 30, 1999)
Dr . S . Sewerin (EI)(until Dec . 31, 1999)
Dr . H. Seyfarth (E2)
Prof . Dr . K . Sistemich (E2)(apl . Prof. at the Univ . of Cologne)
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Prof. Dr . J. Speth (TH)(Prof. at the Univ . of Bonn
DI R. Stassen (LI)
Dr . J . Stein (E2)
Dr . S . Steininger (TH)until August 31, 1999
G. Sterzenbach (El)
Dr . H. Stockhorst (LI)
Prof. Dr . H. Ströher (E2)(apl . Prof . at the Univ . of Mainz
Dr . R . Töne (LI)
DI T. Vashegyi (LI)
Dr . R . Wagner (LI)until May 31, 1999
M. Walzl (TH)since October 5, 1999
DP Z . Wang (TH)
Dr . K .-H. Watzlawik (Da)
Dr . A. Wirzba (TH)since October 1, 1999
Dr . M. Wolke (El)
Dr . E . Zaplatine (LI)
Technical and Administrative Staff:
P. Birx (LI)R . Bley (Ad)H.G. Böge (LI)M. Böhnke (LI)W. Borgs (E2)H. Borsch (LI)R. Brings (LI)G. Brittner (Ec)P. Brittner (LI)until March 31, 1999E. Brökel (Ec)J . But (Ws)M . Comuth (Ad)L. Conin (LI)B. Dahmen (LI)Ch. Deliege(LI)W. Derissen (Cd)Ni Dolfus (Ec)G. D'Orsaneo (E2)R. Enge (LI)J . Engel (LI)P . Engels (LI)W. R . Ermer (E2)
W. Ernst (Ec)K. Esser (Ad)H.J . Etzkom (LI)H.P . Faber (LI)G. Fiori (Dt)H.-W. Firmenich (Ws)G. Gad (LI)D. Gehsing (LI)S . Geister (Cd)G. Göbbels (Rp)H. Hadamek (Ws)A. Hanlacher (Dt)M.G. Holona (Ws)K.D. Jach (LI)H.M. Jäger (El)H.J . Jansen (Ws)R. Janssen (Ad)M. Karnadi (Da)R. Klein (El)K. Krafft (Rp)M. Kremer (Ws)Th . Krings (Dt)since July 5, 1999G. Krol (LI)K .P . Kruck (LI)M. Küven (Ws)K.G. Langenberg (LI)W. Lorenz (Ad)G. Lürken (Ec)H. Metz (Dt)A. Müller (LI)M. Müskes (LI)until July 2, 1999R. Neilen (Ec)J . Pfeiffer (Dt)H.J. Probst (Rp)H. Pütz (LI)A. Retz (Cd)A. Richert (LI)U. Rindfleisch (Cd)G. Roes (Ad)B. Rogozik (LI)N. Rotert (LI)D. Ruhrig (LI)Th. Sagefka (LI)M. Schaaf (LI)Jos . Schmitz (Ws)Jürg . Schmitz (LI)F . Schultheiß (Ws)M. Simon (LI)H. Singer (LI)K. Sobotta (LI)D.W. Spölgen (Ws)J . Strehl (Ws)E. Tesch (Ad)K.P . Wieder (E2)K. Winkler (Ec)J .D. Witt (LI)H.W . Zens (LI)
215
(El) Institute for Experimental Nuclear Physics 1(E2) Institute for Experimental Nuclear Physics 2(Th) Institute for Theoretical Nuclear Physics(LI) Large Nuclear Physics Instruments(Ad) Administration(Cd) Construction and Design(Da) Data Acquisition Group(Dt) Detector and Target Laboratory(Ec) Electronics(Rp) Radiation Protection(Ws) Mechanical Workshop
216
Research Visitors(for one week to sht months):
Dr. A. Akushevich (Th)from September 25 to October 23, 1999(Nat . Center of Part. and High Energy Phys .,Minsk, Russia)
Dr. A. Anisovich (Th)from October 3 to October 31, 1999(Petersburg Nucl . Phys . Inst .,Gatchina, Russia)
Prof. T. Barnes (Th)(DFG-Fellow)since September 1, 1999(University of Tennessee, USA)
Dr. S . Barsov (E2)from January 10 to March 7, 1999from March 14 to May 16, 1999from September 8 to November 7, 1999(St . Petersburg Nucl . Phys . Inst ., Gatchina, St . Petersburg)
Dr. C.T . Chan (Th)(DAAD-fellow)from November 23 to December 16, 1999(National Taiwan University, Taipei)
Prof. V. Chernyshev (E2)from February 21 to Mai 2, 1999from November 14 to 28, 1999(Institute for Theoretical and Experimental Physics,Moskau)
Dr . B. Chiladze (E2)from February 27 to March 27, 1999(High Energy Phys . Inst ., Tbilisi State University, Tbilisi,Georgien)
C.K. Chua (Th)(DAAD-fellow)from December 14 to December 18, 1999(National Taiwan University, Taipei)
Dr . M . Chumakov (E2)from January 17 to March 14, 1999(Institute for Theoretical and Experimental Physics,Moskau)
Prof. S . Drozdz (Th)from May 16 to July 7, 1999from November 8 to November 15, 1999(University of Krakow, Poland)
Prof. J .W. Durso (Th)from May 31 to August 1, 1999(Mount Holyoke College, Hadley, MA, USA)
S. Dymov (E2)from January 24 to February 7, 1999(Joint Inst. for Nucl . Res ., Dubna, Moskau)
Prof. M. Ericson (Th)(AvH-Awardee)from June 26 to July 1, 1999(GERN Geneve, Switzerland)
Prof. T . Ericson (Th)(AvH-Awardee)from June 26 to July 1, 1999(CERN Geneve, Switzerland)
Dr . R . Eher (E2)from January 1 to December 31, 1999(University of Cologne, Germany)
Prof . Dr . S . Fayans (Th)from November 2 to November 7, 1999(Kurchatov Inst . of Atomic Energy,Moscow, Russia)
P . Fedorets (E2)from February 21 to April 18, 1999(Institute for Theoretical and Experimental Physics,Moskau)
Dr . L. Freindl (EI)from Feb . 15 to March 15, 1999from Sept . 6 to Sept . 20, 1999(Kernforschungszentrum Krakau, Poland)
Ing . G. Georgiev (El)from Nov. 17 to Dec . 2, 1999(Inst . for Nucl . Res . and Nucl . Energy, Sofia, Bulgaria)
Prof. Dr. 1. Ginzburg (Th)from January 1 to February 27, 1999(S .L . Sobolev Institute, Novosibirsk, Russia)
Dr. V . Goryachev (E2)from May 2 to 30, 1999(Institute for Theoretical and Experimental Physics,Moskau)
Dr. E . Golubeva (E2)from Mami' 21 to April 18, 1999from July 12 to August 8, 1999(Institute for Theoretical and Experimental Physics,Moskau)
A. Gorski (Th)(DLR-Fellow)from November 8 to December 14, 1999(University of Krakow, Poland)
Dr . V . Grishina (E2)from January 24 to March 7, 1999from April 25 to May 23, 1999from August 15 to September 12, 1999(Institute for Theoretical and Experimental Physics,Moskau)
Dr . L . Gusev (E2)from January 17 to March 14, 1999from May 2 to 30, 1999(Institute for Theoretical and Experimental Physics,Moskau)
217
Dr. C. Hanhart (Th)from June 9 to July 12, 1999(INT Seattle, USA)DP P . Hawranek (EI)from Feb. 22 to March 3, 1999since Sept. 1999 (research sholarship)(Univ . Krakau, Poland)
Prof. Dr . X .G. He (Th)(D-fellow)from December 15 to December 22, 1999(National Taiwan University, Taipei)
Prof. Dr . E . Henley (Th)(AvH-Awardee)from May 25 to June 19, 1999(INT Seattle, USA)
Prof. Dr . B . Holstein (Th)(AvH-Awardee)from March 2 to Juno 15, 1999(University of Massachusetts, USA)
Y. Ilieva (El)Research sholarship(Inst . of Nucl . Res . and Nuci . Energy, Sofia, Bulgaria)
Dr. S . Jeschonnek (Th)from August 15 to September 15, 1999(Jefferson Lab ., Newport News, USA)
DP H. Jungwirth (LI)May 24 to June 3, 1999(NAC, South Africa)
Prof. S . Kamerdzhiev (Th)from October 24 to December 23, 1999(IPPE, Obninsk, Russia)Russia)
Prof. B . Kamys (E2)from March 26 to April 14, 1999(Jagellonian University Cracow, Poland)
Dr. A. Katcharava (E2)from February 28 to March 28, 1999from May 24 to June 14, 1999from September 5 to 26, 1999from November 1 to 21, 1999(Joint Inst . for Nucl . Res ., Dubna, Moskau)
Dr. St . Kistryn (El)from Sept . 5 to Sept . 23, 1999(Univ . Krakau, Polen)
Dr. St . Kliczewski (El)from Feb . 14 to March 20, 1999from Aug. 29 to Sept. 23, 1999(Kernforschungszentrum Krakow, Poland)
W. Klimala (EI)Research sholarship(Jagellonian Univ . of Krakow, Poland)
Dr. D. Kolev (El)from Feb. 8 to April 3, 1999from Sept . 1 to Sept . 28, 1999(University of Sofia, Sofia, Bulgaria)Prof. V . Komarov (E2)from February 21 to March 22, 1999from May 24 to Juno 27, 1999from September 1 to 18, 1999(Joint Inst . for Nucl . Res ., Dubna, Moskau)
Prof. L . Kondratyukfrom January 24 to March 7, 1999 (Th)from April 25 to May 23, 1999 (E2)from August 15 to September 9, 1999 (E2)from November 14 to December 5, 1999 (E2)(Institute for Theoretical and Experimental Physics,Moskau)
Prof. V. Koptev (E2)from January 6 to 20, 1999from January 31 to May 31, 1999from August 25 to October 25, 1999(St . Petersburg Nucl . Phys . Inst., Gatchina, St . Petersburg)
Dr . Y . Korotaev (LI)March 12 to March 27, 1999(JINR, Dubna, Moskau)
Dr . A. Kovalev (E2)from March 10 to April 7, 1999(St. Petersburg Nucl . Phys . Inst ., Gatchina, St . Petersburg)
DP P. Kowina (El)since April 22, 1999Research sholarship(Univ . of Katowice, Poland)
Dr. V. Kozlov (EI)from Dec. 11 to Dec . 16, 1999(Moscow State University, Russia)
Dr. V . Kramarenkofrom Dec . 11 to Dec . 16, 1999(Moscow State University, Russia)
Dr . P. Kravtsov (E2)from January 17 to April 14, 1999from August 8 to October 6, 1999(St . Petersburg Nun Phys . Inst., Gatchina, St . Petersburg)
Dr . F . Krawczyk (LI)from May 31 to July 16, 1999(LANSCE, Los AI os, USA)
Prof. Dr . A. Kudryavtsev (Th)from March 29 to April 27, 1999from October 26 to November 25, 1999(ITEP Moscow, Russia)
Dr . S . Kulagin (Th)from April 25 to May 26, 1999(Russische Akademie d . Wissenschaften, Moscow,Russia)
218
Dr. A. Kulikov (E2)from February 22 to April 12, 1999from May 23 to June 8, 1999from September 1 to 10, 1999(Joint Inst . for Nucl . Res ., Dubna, Moskau)
Dr. V. Kurbatov (E2)from January 21 to February 18, 1999from September 2 to 14, 1999from November 1 to 21, 1999(Joint Inst . for Nucl . Res ., Dubna, Moskau)
Prof. T . Kutsarova (EI)from Feb. 24 to March 14, 1999from Sept . 18 to Oct. 4, 1999(Acad . Science, Sofia, Bulgaria)
Dr . V . Leontiev (E2)from May 23 to June 14, 1999(Joint Inst . for Nucl . Res., Dubna, Moskau)
Dr . H. Liu (Th)from November 21 to December 18, 1999(Ohio University, Athens, USA)
Dr. G. Macharashvili (E2)from February 28 to March 28, 1999from May 24 to June 14, 1999from September 1 to 15, 1999from November 7 to 21, 1999(Joint Inst . for Nucl . Res ., Dubna, Moskau)
Dr . A. Magiera (El)from Feb . 24 to March 3, 1999since July 1, 1999(Kernforschungszentrum Krakau, Poland)
J . Majewski (El)from June 19 to July 19, 1999from Aug . 14 to Sept . 13, 1999from Oct . 17 to Dec . 13, 1999(Jagellonian Univ . of Krakow, Poland)
Prof. G. Martinska (El)from Sept . 13 to Sept . 21, 1999(Univ . of Kosice, Slowakia)
Dr . S . Merzliakov (E2)from January 18 to May 3, 1999from July 7 to August 8, 1999from September 19 to December 23, 1999(Joint Inst. for Nucl . Res ., Dubna, Moskau)
W. Migdal (El)from Aug . 23 to Aug . 30, 1999from Nov . 15 to Dec . 10, 1999(Jagellonian Univ . of Krakow, Poland)
Dr . S . Mikirtytchiants (E2)from January 1 to April 30, 1999from August 25 to September 26, 1999(St. Petersburg Nucl . Phys . Inst., Gatchina, St. Petersburg)
A. Misiak (El)from June 19 to July 19, 1999(Jagellonian Univ . of Krakow, Poland)
Dr. P . Moskal (El)from May 7 to Nov . 5, 1999Research sholarship(Jagellonian Univ . of Krakow, Poland)Prof. Dr. M. Musalchanov (Th)(INTAS-Fellow)from August 13 to August 30, 1999(Tashkent University, Uzbekistan)
Prof. Dr . K. Nakayama (Th)from July 1 to August 31, 1999(University of Georgia, Athens, USA)
Dr . V . Nelyubin (E2)from January 13 to March 24, 1999from April 18 to May 16, 1999from August 25 to October 24, 1999(St . Petersburg Nucl . Phys . Inst., Gatchina, St . Petersburg)
Prof. M. Nioradze (E2)from February 27 to March 27, 1999from September 8 to 15, 1999from November 8 to 22, 1999(High Energy Phys . Inst ., Tbilisi State University, Tbilisi,Georgien)
Dr. L . Onischenko (LI)from June 25 to July 20, 1999(JINR, Dubna, Moskau)
Dr. S . Orfanitskifrom Dec . 11 to Dec . 16, 1999(Moscow State University, Russia)
T. Pappfrom November 15 to December 3, 1999(ATOMKI, Debrecen, Hungary)
Prof. Dr . Pauchy W .-Y . Hwang (Th)(DAAD-fellow)from December 14 to December 18, 1999(National Taiwan University, Taipei)
Dr . L . Pentchev (El)from Feb. 23 to March 19, 1999from Aug. 30 to Sept . 12, 1999(INRE, Sofia, Bulgaria)
Dr . O. Petrus (E2)from January 24 to July 18, 1999from August 18 to September 17, 1999from December 1 to 31, 1999(Joint Inst . for Nucl . Res ., Dubna, Moskau)
Dr . K . Pysz (E2)from March 15 to April 12, 1999(Jagellonian University Cracow, Poland)
219
Dr . A. Rakhirnov (Th)(DAAD-Fellow)from August 21 to Oktober 20, 1999(Tashkent University, Uzbekistan)
Dr . F. Rathmann (E2)from January 1 to December 31, 1999(University of Erlangen, Germany)
B. Rimarzig (E2)from May 17 to 29, 1999(Forschungszentrum Rossendorf, Dresden)
M. Rossewij (El)Research sholarship(Utrecht Univ ., The Netherlands)
Dr . Z. Rudy (E2)from March 22 to April 19, 1999from June 7 to 23, 1999(Jagellonian University Cracow, Poland)
M. Sawa (Th)from June 16 to July 17, 1999(Marie Curie-Sklodowska University Lublin,Poland)
Dr . M. Siemasczko (El)from Feb . 14 to 21, 1999from April 6 to 23, 1999(University of Katowice, Poland)
Dr . R . Siudak (El)from Feb . 14 to March 20, 1999from Aug . 29 to Sept. 20, 1999(Jagellonian Univ . of Krakow, Poland)
Dr. F . Steffens (Th)from November 3 to November 19, 1999(University of Sao Paulo, Brasil)
Prof. A. Strzalkowski (E2)from March 26 to April 6, 1999(Jagellonian University Cracow, Poland)
Dr. A. Szczurek (Th)(DLR-fellow)from April 11 to May, 1999from October 21 to November 20, 1999(Univ . of Krakow, Poland)
Dr. G. Tertychny (Th)from October 24 to December 23, 1999(IPPE, Obninsk, Russia)
Dr. Varese Timoteo (Th)from June 21 to September 3, 1999(University of Sao Paulo, Brasil)
Dr. R . Tsenov (EI)from Feb . 15 to March 20, 1999(University of Sofia, Sofia, Bulgaria)
Prof. Dr . T . Ueda (Th)(DLR-Fellow)from December 5 to December 12, 1999(Ehime University, Japan)
V. Uleshenko (Th)(DLR-fellow)from October 21 to November 20, 1999(Univ . of Krakow, Poland)
DP M. Ulicny (El)since Sept . 13, 1999Research sholarship(Univ . of Kosice, Slowakia)
Dr . J . Urban (El)from Sept . 13 to Sept . 28, 1999(Univ . of Kosice, Slowakia)
Dr . W. Urban (El)from Feb. 4 to 14, 1999(Inst . of Exp . Physics, Univ . of Warsaw, Poland)
Dr. Y . Uzikov (E2)from January 31 to February 28, 1999from April 25 to May 25, 1999from October 26 to December 7, 1999(Joint Inst . for Nucl . Res ., Dubna, Moskau)
Dr. A. Vassiliev (E2)from January 24 to February 7, 1999from February 28 to May 2, 1999from August 25 to December 19, 1999(St . Petersburg Nucl . Phys . Inst ., Gatchina, St . Petersburg)
Prof. Dr. E . Veit (Th)(DLR-Fellow)from September 19 to October 17, 1999(University Rio Grande do Sul, Porto Alegre, Brasil)
Dr . Y . Venkova (El)from Sept . 16 to Oct . 20, 1999(Bulgarische Akademie der Wissenschaften, Sofia,Bulgarien)
Dr . G. de Villiers (LI)from June 8 to August 31, 1999(NAC, South Africa)
Dr . A. Wirzba (Th)since October 1, 1999(SUNY at Stony Brook, USA)
Dr . M . Wojcik (Th)from May 24 to July 3, 1999(University of Krakow, Poland)
A. Wronska (EI)from Sept . 5 to 23, 1999from Nov. 15 to Dec . 22, 1999(Jagellonian Univ . of Krakow, Poland)
220
Dr . S . Yaschenko (E2)from February 28 to March 22, 1999from November 1 to 21, 1999(Joint Inst. for Nucl . Res ., Dubna, Moskau)
Dr. B.G. Zakbarov (Th)(DFG-fellow)from June 4 to September 3, 1999(Landau Inst. for Theor . Phys ., Moscow, Russia)Dr. B. Zalikhanov (E2)from February 21 to April 12, 1999from August 1 to September 14, 1999from November 24 to December 31, 1999(Joint Inst . for Nucl . Res ., Dubna, Moskau)
Dr. V. Zoller (Th)(DFG fellow)from October 15 to December 23, 1999(FIEP, Moskow, Russia)
Prof. W. Zipper (El)from May 6 to 16, 1999(University of Katowice, Poland)
Dr . N. Zhuravlev (E2)from February 28 to March 22, 1999(Joint Inst . for Nucl . Res ., Dubna, Moskau)
P. Zupranski (El)from Aug 23 to Sept . 3, 1999(Soltau Institute for Nuclear Studies, Warschau, Poland)
Dr. I . Zychor (E2)from January 25 to February 24, 1999from March 29 to June 28, 1999from October 15 to November 19, 1999(Soltau Inst . for Nucl . Studies, Swierk-Otwock, Poland)
221
222
X. PUBL1CATIONS
Journals
IKP-99-11-1Achenbach, P ., Ahrens, J ., Beck, R ., Half, S . J ., Hejny, V .,Kotulla, M ., Krusche, B ., Kuhr, V ., Lecke!, R ., Metag, V.,Novotny, R ., Olmos de Leön, V ., Owens, R. 0 ., Rambo, F .,Schmidt, A ., Sioglaczek, U ., Ströher, H ., Weiß, J., Wissmann, F .,Wolf, M.Near threshold photoproduction of n mesons from 4He
Eur . Phys . J . A 6 (1999) 83-8920 .50 .0
IKP-99-11-2Ahrens, J ., Beck, R ., Fuchs, M., Härter, F ., Hall, S. J ., Keine, J . D.,
Krusche, B ., Metag, V ., Röbig-Landau, M ., Ströher, H.Single and double rt0 -photoproduction from the deuteronEur . Phys . J . A 6 (1999) 30920 .50 .0
1KP-99-11-3Altmeier, M . ; Bauer, F. ; Bisplinghoff, J . ; Bissel, T. ; Bolimann, R .;Busch, M . ; Büßer,
Gelberg, T. ; Demirörs, L. ; Diehl, 0 .;Dohrmann, F. ; Engelhardt, H . P. ; Eversheim, P. D . ; Felden, 0 .;Gebet, R . ; Glende, M . ; Greiff, J . ; Groß, A. ; Groß-Hardt, R .;Hinterberger, F. ; Jahn, R . ; Jeske, M . ; Jenas, E . ; Krause, H. ; Lahn
Langkau, R . ; Lindemann, T. ; Lindlein, J . ; Maier, R . ; Maschuw,R.; Mayer-Kuckuck, T. ; Meinerzhagen, A .; Nähle, 0 . ; Pfeif, M .;Prasuhn, D. ; Rohdjeß, H . ; Rosendaal, D . ; Rossen von, P. ; Sanz, B .;Schirm, N . ; Schulz-Rojahn, Mg Schwarz, V. ; Scabel, W. ; Thomas,S.; Trelle, H . J . ; Weise, E . ; Wellinghausen, A . ; Wiedmann, W .;Wollen K. ; Ziegler, R.A helical scintillating fiber hodoscopeNuclear Instruments & Methode in Physics Research (Section A)431, No .3 - July 21, 199920 .35 .0
IKP-99-11-4Anagnostopoulos, D ., Augsburger, M ., Borchert, G., Castelli, C.,Chatellard, D ., EI-Khoury, P., Egger, J . R, Gerke, H ., Gotta, D.,Hauser, P., Indelicato, R, Kirch, K., Lenz, S., Nelms, N ., Rashid, K.,Schult, 0 . W. B ., Siems, Th ., Simons, L. M.New Results en Strong-Interaction Effects in Antiprotonic HydrogenNuclear Physics A 655 (1999) 305c20 .50 .0
1KP-99-11-5Anagnostopoulos, D ., Augsburger, M., Borchert, G ., Chatellard, D.,Egger, J . P., EI-Khoury, P., Gerke, H ., Sofia, D., Hauser, P.,Indelicato, P., Kirch, K., Lenz, S., Rashid, K ., Siems, Th.,Simons, L. M.Measurement of the Strong-Interaction Parameters in AntiprotonicHydrogen and Probable Evidence for an lnterference with InnerBremsstrahlungNuclear Physics A 658 (1999) 14920 .50 .0
1KP-99-11-6Anagnostopoulos, D., Augsburger, M ., Borchert, G ., Chatellard, D.,Egger, J . P., EI-Khoury, P., Gorke, H ., Gotta, D ., Hauser, P.,Indelicato, R, Kirch, K ., Lenz, S,, Siems, Simons, L. M.Measurement of Strang interaction Parameters in AntiprotonicHydrogen and DeuteriumHyperfine 6nteractions 118 (1999) 5920.50 .0
1KP-99-11-7Anagnostopoulos, D ., Augsburger, M ., Borchert, G ., Chatellard, D .,Egger, J . P., EI-Khoury, P., Gorke, H ., Gotta, D ., Hauser, P.,Indelicato, P., Kirch, K., Lenz, S., Rashid, K., Siems, Th .,Simons, L . M.Measurement of the Strong-Interaction Parameters in AntiprotonicDeuteriumPhys . Lett . B 461 (1999) 41720 .50 .0
iKR-99-11-8Anagnostopoulos, F., Augsburger, M ., Borchert, G ., Castein, C .,Chatellard, D ., Egger, J . -P., EI-Khoury, R, Gorke, H ., Gotta D.,Hauser, P., Indelicato, P., Kirch, K ., Lenz, S ., Nelms, N., Rashid, K.,Siems, Th . and L. M . SimonsBalmer a transitions in antiprotonic hydrogen and deuteriumNucl. Phys . A 660 (1999) 28320 .50 .0
IKP-99-11-9Aphecetche, L., Appenheimer, M ., Averbeck, R ., Charbonnier, Y .,Delagrange, H ., d"Enterria, D ., Diaz, J ., Döppenschmidt, A.,
Hlavac, S ., Hoefman, M., Holzmann, R., Kugler, A., Lefövre, F .,Löhner, H ., Marin, A ., Martinez, G ., Matulewicz, T., Metag, V.,Novotny, R ., Ostendorf, R . W., Schutz, Y ., Siemssen, R . H .,Simon, R . S ., Stratmann, R ., Ströher, H ., Tlusty, P ., Turnst, R ., vanGoethem, M . J ., Vogt, P., Wagner, V ., Weiß, J ., Wüschet, H . W .,Wissmann, F., Wolf, A. R . and Wolf, M .,Photon Production in Heavy-Ion Collisions dose to the PionThresholdPhys . Lett . B 461 (1999) 2320 .50 .0
IKP-99-11-10Aphecetche, L ., Appenheimer, M ., Averbeck, R., Charbonnier, Y.,Delagrange, H ., Diaz, J ., Döppenschmidt, A ., Gudima, K. K .,Hlaväe, S ., Hoefman, M ., Holzmann, R ., Kugler, A ., Lefövre, F.,Löhner, H ., Marin, A ., Martinez, G ., Matulewicz,
Metag, V.,Novotny, R ., Ostendorf, R . W., Ploszajczak, M ., Schutz, Y.,Siemssen, R . H ., Simon, R . S ., Stratmann, R ., Ströher, H .,Tlusty, P., Toneev, V., Turrisi, R ., van Goethem, M . J., Vogt, R,Wagner, V., Weiß, J ., Wilschut, H . W., Wissmann, F., Wolf, A . R.,Wolf, M.,Deep-Subthrehold and rc° Production Probing Pion Dynamics inthe Reaction Ar+Ca at 180 AMeVPhys . Rev. Lett . 83 (1999) 1538-154120 .50 .0
IKP-99-11-11Baru V., Haidenbauer J ., Hanhart C ., Kudryavtsev A., Moskal P.,Speth J.0n Production of n' Mesons in pp Cellisions Gase to ThresholdEur. Phys. J . A6 (1999)20 .80 .0
IKP-99-11-12Baur G ., Leuschner A.Bethe-Heitler Cross-Section for Very High Photon Energies andLarge Muon Scaffering AnglesEur. Phys . J . C8 (1999) 631-63520 .80 .0
223
KP-99-11-13Baur G ., Henken K ., Trautmann D.Photon-Photon and Photon-Hadron Interactions at RelativistieHeavy Ion CollidersPart and Nuel . Phys . 42 (1999) 357-36620 .80 .0
KP-99-11-14Bellemann, F., Berg, A ., Bisplinghoff, J ., Bohlscheid, G ., ERnst, J .,Henrich, C., Hinterberger,
!bald, R ., Jahn, R ., Jarczyk, L .,Joosten, R ., Kozela, A., Machner, H ., Magiera, A ., Maschuw, R.,Mayer-Kuckuk, T., Nierüber, G ., Munkel, J., von Neumann-Cosel, P.,Rosendaai, D ., von Rossen, P., Schnitker, H ., Scho, K ., Smyrski, J .,Strzalkowski, A ., Töne, R ., and Wilkin, C.Pion-pion p-wave dominante in the pd--33Herr.rC reaction nearthresholdPhys .Rev. C60 (1999) 06100220 .45 .0
KP-99-11-15Bernard V., Kaiser N ., Meißner Ulf-G.Novel Approach to Pion and Eta Production in Proton-ProtonCollisions nearThresholdEuro . Phys . J . A4 (1999) 25920 .80 .0
KP-99-11-16Betigeri, M ., Bialkowski, E., Bojowald, H ., Budzanowski, A .,Chatterjee, A ., Drochner, M ., Ernst, J ., Förtsch, S ., Freindl, L .,Frekers, D ., Garske, W ., Grewer, K., Hamacher, A., Igel, S ., Ilieva,J ., Jarczyk, L ., Jochmann, M., Kemmerling, G., Kilian, K .,Kliczewski, S ., Klimala, W., Kolev, D ., Kutsarova, T., Lieb, J .,Lippert, G ., Machner, H ., Magiera, A ., Nann, H ., Pentchev, L .,Plendl, H .S ., Protic, D ., Razen, B ., von Rossen, P., Roy, B.J .,Siudak, R ., Smyrski, J ., Srikantiah, R .V., Strzalkowski, A ., Tsenov,R ., Zolnierczuk, P.A . Zweit, K.The Germanium Wall of the GEM Detector SystemMach Instr. and Methods in Phys . Res . A421 (1999) 44720 .45 .0
IKP-99-11-17Betigeri, M., Bojewald, H ., Budzanowski, A ., Chatterjee, A.,Drochner, M ., Ernst, J ., Färtsch, S ., Freindl, L., Frekers, D., Garske,W., Grewer, K ., Hamacher, A ., Hawash, M., Igel, S ., Ilieva, J .,Jarczyk, L., Kemmerling, G ., Kilian, K ., Kliczewski, S ., Klimala, W.,Kolev, D ., Kutsarova, T., Lieb, J ., Lippert, G ., Machner, H ., Magiera,A ., Maier, R ., Nann, H ., Plendl, H .S., Protic, D ., Razen, B ., vonRossen, P., Roy, B .J ., Siudak, R ., Smyrski, J ., Strzalkowski, A.,Tsenov, R ., Zolnierczuk, P.A.Precise Momentum Determination of the Extemal COSY ProtonBeam near 1930 MeV/cNucl . Instr. Methods in Phys . Res . A426 (1999) 24920 .45 .0
IKP-99-11-18Böckmann R., Hanhart C ., Krehl 0 ., Krewald S ., Speth J.The rcNN Vertex Function in a Meson-Theoretical ModelPhys . Rev. C60 (1999) 05521220 .80 .0
IKP-99-11-19Borgs, W. ; Cassing, W . ; Hartmann, M . ; Hermes, T. ; Jarczyk, L .;Kamys, B . ; Koch, H . R . ; Kulessa, Maier, R . ; P. ; Ohm, H . ; Pfeiffer, J .;Prasuhn, D . ; Pysz, K . ; Rudy, Z . ; Schult, O . W. B . ; Strzalkowski, A .;Uozumi, Y. ; Zychor, I.Measurement of the Mtetime of heavy A hypemuclei with the reooilshadow method and intemal targets in the storage ring COSY-JülichNuciear Instruments an Methods in Physics Research A 420 (1999)356-36520 .35 .0
iKP-99-11-20Cassing, W ., Jarczyk, L., Kamys, B ., Kulessa, P., Rudy, Z .,Schult, O. W. B. and Strzalkowski, A.On the
= 1/2 rufe in the AN NN reactionEur . Phys . J . A5, 127 (1999)
KP-99-11-21Chen B .Q., Ma Z .Y., Grümmer F., Krewald S.Neutron-rieh Nuclei in Density Dependent Relativistic Hartree-FockTheory with Isovector MesonsPhys . Lea . 8455 (1999) 1320.80 .0
iKP-99-11-22Cloth, P. ; Filges, D . and the members of the ZEUS Collaboration:Exclusive Electroproduction of pc' and J/v Mesons at HERAEur. Phys . J . C 6 (1999) 603-62720 .48 .0
IKP-99-11-23Cloth, P. ; Filges, D . and the members of the ZEUS Collaboration:ZEUS Resuite an the Measurement and Phenomenology of F2 atLow x and Low 02Eur. Phys . J . C 7 (1999) 609-63020 .48 .0
IKP-99-11-24Cloth, P. ; Filges, D . and the members of the ZEUS Collaboration:Measurement of Jet Shapes in High-Q 2 Deep Inelastic Scattering atHERAEur. Phys . J . C 8 (1999) 367-38020 .48 .0
IKP-99-11-25Cloth, P. ; Filges, D . and the members of the ZEUS Collaboration:Measurement of Multiplicity and Momentum Spectra in the Currentand Target Regions of the Breit Frame in Deep lneiastic Scatteringat HERAEur.Phys . J .Cll (1999) 251-270/Report, DESY-99-041, March 199920 .48 .0
IKP-99-11-26Cloth,
Filges, D . and the members of the ZEUS Collaboration:Measurement of High-(22 Neutral-Current e`p Deep InelasticScattering Cross Sections at HERAEur.Phys .J .Cll (1999) 427-445/Report, DESY-99-056, May 199920 .48.0
224
IKP-99-11-27Drochner, M ., Ernst, J ., Förtsch, S ., Freindl, L, Frekers, D., Garske,W., Grewer, K ., Igel, S., Jahn, R ., Jarczyk, L, Kemmerling, G .,Kilian, K., Kliezewski, S ., Klimala, W., Kolev, D., Kutsarova,Lippen, G ., Machner, H ., Maier, R ., Nake, C ., Razen, B ., vonRossen,
Roy, B.R., Sehe, K., Siudak, R., Srnyrski, J .,Strzaikowski, A ., Tsenov, R., Zolnierczuk, RA., Z
K.Comment an «Total and Differential Cross See )ns of p+p---xs+dReactions Down to 275 keV above ThresholdPhys. Rev. Lett. 83 (1999) 169320 .45 .0
IKP-99-11-28Drozdz S., Ruf F., Speth J ., Wojcik M.lmprints of Log-Periodic Seif-Similarity in the Stock MarketEurop . Phys . Joum . B10 (1999) 589-59320 .80 .0
IKP-99-11-29Elster Ch ., Schadow W., Nogga A ., Glöckle W.Three Body Sound State Calculations without Angular MomentumDecompositionFew Body Systems 27 (1999) 8320 .80 .0
iKP-99-11-30Elster Ch ., Weppner S .P.Reply to Comment Energy Dependence of the NN t-matrix in theOptical Potential for Elastic N-Nucleus ScatteringPhys . Rev . C59 (1999), 181620 .80 .0
IKP-99-11-31Enke, M . ; Filges, D . ; Galin, J . ; Goldenbaum, F. ; Herbach, C .-M .;HHscher, D . ; Jahnke, U . ; Letourneau, A . ; Lott, B . ; Neef, R .-D .;Nünighoff, K . ; Paul, N . ; Pöghaire, A . ; Pienkowski, L . ; Schaaf, H .;Schapiro, 0 . ; Sterzenbach, G . ; Tietze, A .:Evolution of a Spaltaffen Reaction : Experiment and Monte CarloSimulationNucl .Phys . A657 (1999) 317-33920 .90 .0
!KP-99-11-32Epelbaum E ., Glöckle W., Krüger A ., Meißner Ulf-G.Effective Theory for the Two-Nucleon SystemNucl . Phys . A645 (1999) 41320 .80 .0
IKP-99-11-33Epelbaum E ., Meißner Ulf-G.Charge Independenee Breaking and Charge Symmetry Breaking inthe Nucleon-Nucleon Interaction from Effective Field TheoryPhys. Lett. 8461 (1999) 28720 .80 .0
IKP-99-11-34Fettes N ., Meißner Ulf-G ., Steininger S.On the Size of lsospin Violation in Low-Energy Pion-NukleonScatteringPhys . Lett . 8451 (1999) 23320 .80 .0
IKP-99-11-35Genas G .C ., Hemmert T.R., Ktorides C.N ., Poulis G .I.The Delta Nucleon Transition Form-Factors in Chiral PerturbationTheoryPhys . Rev. D60 (1999) 05402220.80 .0
IKP-99-11-36Goldenbaum, F. ; Morjean, M . ; Chevallier, M . ; Cohen, C .;Dauvergne, D . ; Della-Negra, S . ; Galin, J . ; Jacquet, D. ; Kirsch, R .;Lienard, E . ; Lott, 13 . ; Perier, Y. ; Poizat, J .C . ; Prevot, G . ; Remillieux,J . ; Schmaus, D . ; Toulemonde, M .:Fiselen Time Evolution with Excitation Energy from a CrystaiBlocking ExperimentPhys . Rev. Lett . 82, Neue 25 (1999) 501220.48 .0
KP-99-11-37Hassan, A . Brinkmann, K .-Th ., Kuhlmann, E ., Kilian, K., Oelert, W .,Ruderburg, E.A Multifunctional Cryo-Target for the Extern& COSY-ExperimentsNuci . instr. & Meth . in Phys . Res. A425 (1999) 40320.45 .0
IKP-99-11-38Hemmert T.R ., Kubis B ., Meißner Ulf-G.Strange Chiral Nucleon Form FactorsPhys . Rev. C60 (1999) 04550120 .80 .0
iKP-99-11-39Hencken K., Trautmann D ., Baur G.Calculation of Higher Order Effects in Electron-Positron Productionin Relativistic Heavy Ion CollisionsPhys . Rev. C59 (1999) 841-84420 .80 .0
!KP-99-11-40Hencken K., Trautmann, D ., Baur G.Bremsstrahlung from Electrons and Positrons in PeripheralRelativistic Heavy Ion CollisionsPhys . Rev. C60 (1999) 03490120 .80 .0
IKP-99-11-41Hoffmann, W . ; Bienen, J . ; Filges, D . ; Schmitz, Th .:TLD-300 Dosimetry in a 175 MeV Proton BeamRadiation Protection Dosimetry, Vol . 85, Nee . 1-4 (1999) 341-34320 .48 .0
IKP-99-11-42Ivanov 1 ., Nikolaev N .N ., Pronyaev A.V., Schäfer W.Diffraction Driven Steep Rise of Spin Structure FunctionG(LT)=G(1)+G(2) at Small X and Dis Sum RulesPhys . Lett . B 457 (1999) 218-22620 .80 .0
IKP-99-11-43Ivanov 1 ., Nikolaev N .N.Diffractive S and D-wave Vector Mesons in Deep InelasticScatteringJETP Lett . 69 (1999) 29420 .80 .0
225
lKP-99-11-44lvanov L, Nikolaev N .N ., Pronyaev A .V., Schäfer W.How Unitarity Im es a Steep Small-X Rise of Spin StructureFunction G(LT)=G(1)+G(2) and Breaking of DIS Surn RulesPhys. Rep. 320 (1999) 17520.80 .0
iKP-99-11-45Jahnke, U .; Bohne, W .; v. Egidy, T. ; Figuera, P. ; Galin, J .;Goldenbaum, F. ; Hilscher, D . ; Jastrzebski, J . ; Lott, Morjean, M .;Pausch, G . ; Peghaire, A . ; Pienkowski, L. ; Polster, D . ; Proschitzki,S . ; Quednau, B . ; Rossner, H . ; Schmid, S. ; Schmid, W.:Prevalence of Fission and Evaporation in the Decay of HeavyNuclei Excited up to 1000 MeV with Energetic AntiprotonsPhys . Rev. Lett . 83 (1999) 495920 .48 .0
IKP-99-11-46Krehl 0., Papp R ., Durso J .W., Aouissat Z ., Chanfray G ., Schuck P.,Speth J ., Warnbach J.Enhancement of rtA-nutA Threshold Cross Sections by in-mediumrtrt Final State InteractionPhys . Rev. C59 (1999) 8123720 .80 .0
1KP-99-11-47Krehl 0., Hanhart C ., Krewald S., Speth J.What does p exchange in ltN Scattering mean?Phys . Rev. C60 (1999) 05520620 .80 .0
IKP-99-11-48Kubis B ., Hemmert TA ., Meißner Ulf-G.Baryon Form FactorsPhys . Lett . B456 (1999) 24020 .80 .0
1KP-99-11-49Lieder, R .M ., Venkova, Ts ., Utzelmann, S ., Gast, W ., Schnare, H .,Spohr, K ., Hoemes, P., Georgiev, A., Bazzacco, D ., Menegazzo, R .,Rossi-Alvarez, C., de Angelis, G ., Kaczarowski, R ., Rzaca-Urban,T., Morek, T., Marti, G .V., Maier, K .H ., and Frauendort, S.Observation of a (v7/Z[514] 2 Crossing in la°OsNucl . Phys . A645 (1999) 46520 .10 .0
!KP-99-11-50Machner H ., Haidenbauer J.Meson Production Close to ThresholdJ . Phys . G25 (1999) R24120 .45 .0, 20 .80 .0
IKP-99-11-51Machner, H ., Razen, B . et al.Efficiency of Solid State DetectorsNucl . Instr. Methode in Phys . Res . A437 (1999) 41920 .45 .0
IKP-99-11-52Meißner Ulf-G ., Weigel H.The Parity-Violation Pion-Nucleon Coupling Constant from aRealistic Three Flavor Skyrme ModelPhys . Lett . B447 (1999) 120 .80 .0
IKP-99-11-53Meinitchouk W.Extraction of twist-four Matrix Elements of the NucleonNucl . Phys. A654 (1999) 584c-587c20.80.0
IKP-99-11-54Müller G ., Meißner Ulf-G.Virtuaf Photons in Baryon Chiral Perturbation TheoryNucl . Phys . B556 (1999) 04550120 .80.0
1KP-99-11-55Nakayama K., Durso J .W., Haidenbauer J ., Hanhart C ., Speth J.t -Meson Production in Proton-Proton CollisionsPhys . Rev. C60 (1999) 05520920 .80 .0
IKP-99-11-56Nikolaev N .N ., Schäfer W., Szczurek A ., Speth J.Do the E866 Drell-Yan Data Change our Picture of the ChiralStructure of the Nucleon?Phys . Rev. D60 (1999) 01400420 .80 .0
IKP-99-11-57Nikolaev N .N ., Zoller V .R.Precocious Asymptopia tor Charm from the Running BFKLJETP Lett. 69 (1999) 18720.80 .0
IKP-99-11-58Nikolaev N .N ., Zoller V.R.The Running BFKL : Resolution of Caldwell is PuzzleJETP Lett . 69 (1999) 10320 .80 .0
IKP-99-11-59Nikolaev N .N ., Pronyaev A.V.Azimuthal Asymmetry as a New Handle an Sigma(L)/Sigma(T) inDiffractive DISPhys . Rev. D59 (1999) 09150120 .80 .0
IKP-99-11-60Oelert, W. (together with the PROMICE/WASA Collaboration atCELSIUS)Observation of Streng Final-State Effects in rc' Production in ppCollisions at 400 MeVPhys . Lett . B446 (1999) 17920 .45 .0
IKP-99-11-61Oelert, W. (together with the PROMICEANASA Coliaboration atCELSIUS)Higher Partial Waves in pp-epgn Near ThresholdPhys . Lett . B458 (1999) 19020 .45 .0
IKP-99-11-62Rossi, G . ; Morse, J . ; Probe, D . : Energy and Position Resolution ofGermanium Microstrip Detectors at X-Ray Energies from 15 to 100keVIEEE Trans . Nucl . Sch, Vol . 46, No . 3 (1999) 76520 .20 .0
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IKP-99-1143Sewerin, S ., Schepers, G ., Balewski, J .T., Budzanowski, A., Eyrich,W., Fritsch, M., Goodman, C ., Grzonka, D., Haidenbauer, J .,Hanhart, C ., Hofmann, M ., Jarczyk, L, Jochmann, M ., Khoukaz,Kilian, K., Köhler, M ., Lister, T., Moskal, P., Gelen, W ., Peilmann, 1 .,Quentmeier, C ., Santo, R., Seddik, U ., Sefzick,
Smyrski, J .,Stinzing, F., Strzaikowski, A., Wilkin, C., Wolke, M ., Wüstner, P., andWyrwa, D.Comparison of A and
Production near Threshold in Proton-Proton CollisionsPhys. Rev. Lea_ Vol . 83, No . 4 (1999) 68220 .50 .0, 20 .80 .0
IKP-99-11-64Utsunomiya H ., Tokimoto Y, Osada K ., Yamagata T., Ohta M ., AokiY., Hirota K ., leki K., Iwata Y., Katori K ., Hamada S ., LuiSchmitt R .P., Typel S ., Baur G.Excitation of Continuum States in 7Li and their Decay by QuantumTunnelingNuol . Phys . A654 (1999) 928c-931o20 .80 .0
1KP-99-11-65Ur, C .A ., Bazzacco, D ., Bolzonella, G .P,, Lunardi, S ., Medina, N .H.,Petrache, CM., Rao, MA ., Rossi-Alvarez, C ., Zhu, LH., deAngelis, G ., De Acuna, D., Napoli, D .R ., Gast, W ., Lieder, R .M .,Rzaca-Urban, T., Wyss, R.Quadrupole Moment of the Yrast Superdeformed Band in 44«dPhys . Rev. C60 (1999)20 .10 .0
IKP-99-11-66Wita H ., Kamada H ., Nogga A ., Glöckle W., Elster Ch ., HüberModern NN Force Predictions tor the Total ND Cross Section up to300 MeVPhys . Rev. 59 (1999) 303520 .80 .0
227
Profi eedings, Reports
IKP-99-12-1Anagnostopoulos, D ., Borchert, G . L ., Chatellard, D., Egger, J . P.,El-Khoury, P., Gotta, D., Hauser, P., Kirch, K ., Schult, O. W . B .,Siems, Th ., Simons, L . M.Direkter Nachweis der Coulomb-Explosion in exotischen AtomenAtomphysik, DPG Heidelberg20 .50 .0
1KP-99-12-2Baldauf, R ., Kleines, H., Kravtsov, A ., Mikirtytchiants, M .,Nekipelov, M., Rathmann, F., Sarkadi, J ., Seyfarth, H ., Vassiliev A .,Zwoll, K .,The slow control System of the Atomic Beam Source atANKEICOSY - An industrial approach based on WinCC and S7PLCs7'h Mt. Conf. on accelerator and !arge experimental physics contra!systems, Triest, 4 . - 8 .10 .199920 .45 .0
IKP-99-12-3Baldauf, R .,
Ermer, W.,
Geisler, S .,
Kleines, H .,
Koch, N .,Koptev ,V., Kovalev, A ., Kravtsov, P., Lorentz, B ., Lorenz, S .,Mikirtytchiants, M., Nekipelov, M.,
Nelyubin, V.,
Paetz gen.Schieck, H ., Rathmann, F., Rindfleisch, U ., Sarkadi, J ., Schult, 0 .,Seyfarth, H ., Steffens, E ., Ströher, H ., Vassiliev, A. and Zwoll, K.:The Polarized Intemal Target for the ANKE Facility at COSY-JülichInt.Workshop on Polarized Sources and Targets (PST99), Erlangen,29 .9 . - 2.10 .199920 .45 .0
IKP-99-12-4Baldauf, R .,
Barsov, S .,
Grishina, V.,
Kleines, H .,
Koch, N.,Kondratyuk, L., Koptev, V., Kovalev, A ., Lorenz, S., Maier, R .,Mikirtytchiants, M ., Nekipelov, M.,
Nelyubin, V.,
Paetz gen.Schieck, H ., Rathmann, F., Sarkadi, J ., Schult, O . W. B .,Seyfarth, H ., Steffens, E ., Stein, H . J ., Vassiliev, A., Wilkin, C . andZwoll, K .:The polarized Atomic Beam Source for the internal Gas Target atANKE/COSYDPG-Frühjahrstagung, Physik der Hadronen und Kerne, Freiburg,22 . - 26 .3 .199920 .45 .0
IKP-99-12-5Balewski, J .,
Daehnick, W .,
Doskow, J .,
Flammang, R.,Haeberli, W ., Lorentz, B ., Meyer, H. 0., Pancella, P. V.,Pollock, R . E ., von Przewoski, B ., Rathmann, F., Rinckel, T.,Saha, S . K., Schwartz, B., Thämgren Engblom, P., Wise, T. für diePINTEX-Kollaboration:2 2 p21t0 with longitudinal beam and target polarizationDPG-Frühjahrstagung, Physik der Hadronen und Kerne, Freiburg,22 . - 26.3 .199920 .50 .0
IKP-99-12-6Bechstedt, U . ; Dietrich, J . ; Henn, K . ; Lehrach, A . ; Maier, R.;Prasuhn, D . ; Schnase, A . ; Schneider, H . ; Stassen, R . ; Stockhorst,H . ; Töne, R.Optical Match Filter for the Stochastic Cooling System of COSY.Proc . PAC 99, New York, 29 .3 .-2 .4 .199920 .30 .0
IKP-99-12-7Betigeri, M . et al.Test of Charge Independence in p+d-3(A=3)+Pion ReactionsProc . PANIC99, Kiwi . Phys . (in press)20.45 .0
1KP-99-12-8Betigeri, M . et al.Test of Isospin Symmetry in NN->dir ReactionsProc . MENU 99, rcN Newsletters (in press)20.45 .0
IKP-99-12-9Betigeri, M . et al.Meson Production in p+d ReactionsProc . STORI99 (in press)20 .45 .0
IKP-99-12-10Bijnens J ., Meißner Ulf-G.Chiral Effective TheoriesMiniproceedings of the meeting on Chiral Effective Theories, BadHonnef, Germany, 30 .11 .-4 .12 .1998, appeared as e-print, hep-ph/9901381 (Jan . 1999)20 .80 .0
IKP-99-12-11Bijnens J., Meißner Ulf-G.Chiral Effective TheoriesMiniproceedings of the meeting on Chiral Effective Theories, BadHonnef, Germany, 30.11 .-4 .12.1998,Phys . BI . 55 (1999) Nr. 220 .80 .0
IKP-99-12-12Böge, H . G . ; Bräutigam, W . ; Bringe, R . ; Gad, N . ; Probst, H . J.Metzger, S . ; Henschel, H . ; Köhn, 0 . ; Lennartz, W.Low Energy Proton Testing of Space Electronies at "Julie"Contrib . RADECS 99, 5'h European Conference on Radiation andits Effects on Components and Systems, Abbaye de Fontevraud,France, September, 13 .-17 .,199920 .30 .0
IKP-99-12-13Borchert, G . L.High Resolution X-Ray Spectroscopy of Exotic Atoms with a Doublyfocussing Crystal Spectrometer2 nh Workshop on Methods and Applications of Curved Crystal C-Ray Optics, Weimar 1999, 4 . - 7 .10 .199920 .50 .0
1KP-99-12-14Borchert, G . L ., Anagnostopoulos, D., Augsburger, M., Castelli, C .,Chatellard, D ., El-Khoury, P., Egger, J . R, Gerke, H ., Gotta, D.,Hauser, P., Indelicato, P., Kirch, K ., Lenz, S., Nelms, N ., Rashid, K.,Schult, O. W . B ., Siems, Th ., Simons, L. M.High Resolution X-Ray Spectroscopy in Light Antiprotonic Atoms1 Euroconference on Atomic Physies at Accelerators APAC 99,Budenheim 1999, 19 . - 24 .9 .199920 .50 .0
228
1KP-99-12-15Borchert, G . L.Erste direkte Beobachtung der Coulomb-Explosion in exotischenAtomen20 . Arbeitstagung ; Energiereiche Stöße, Rieziem, 24 . - 30 .1 .199920 .50 .0
IKP-99-12-16Bräutigam, W. Martin, S . ; Schug, G . ; Senichev, Y. ; Zaplatine, E.Design Considerations for a superconducting Linac as an Option forthe ESSProc . of the IEEE Particle Accelerator Conference 1999, New York,29h' March - 2 hh April, 1999, pp. 3549-355120 .91 .0
1KP-99-1217Bräutigam, W. Martin, S . ; Schug, G . ; Senichev, Y. ; Zaplatine, E.Design Study for SC Proton Linac Accelerating CavitiesProc . of the IEEE Particle Accelerator Conference 1999, New York,29'h March - 2 r'h April, 1999, pp. 959-96120 .91 .0
IKP-99-12-18Bräutigam, W.Diete, W. ; Griep, B . ; Peiniger, M.; Vogel, H . ; vom Stein, P. (ACCELLInstruments GmbH)A Superconducting Accelerating Test Module for the EuropeanSpallation Neutron Source (ESS)Proc . of the IEEE Particle Accelerator Conference 1999, New York,29 'h March - 2"' April, 1999, pp . 957-95820 .91 .0
IKP-99-12-19Bräutigam, W.Bauer, S . ; Diete, W . ; Griep, B . ; Peiniger, M . ; Pekeler, M . ; Vogel, H .;vom Stein, P. (ACCELL Instruments GmbH)Chiaveri, E . ; Losito, R . ; (GERN, Genf)Engineering and Fabrication of a reduced Beta PrototypeSuperconducting Acclerator Module for Forschungszentrum JülichContrib . 9'h Workshop on RF Superconductivity, Santa Fe,November 1-5,199920 .91 .0
IKP-99-12-20Bräutigam, W. ; Felden, 0 . ; Maier, R. ; Martin, S . ; Schnase, A .;Schug, G . ; Stassen, R . ; Zaplatine, E.Design Considerations for the Linac System of the ESSContrib. IBA-14/ECAART-6, Dresden, 26.-30 .6 .199920 .91 .0
IKP-99-12-21Brüggemann, R ., Koptev, V., Kravtsov; P., Lemaitre, S., Lorenz, S .,Nelyubin, V., Paetz gen Schieck, H ., Rathmann, F., Seyfarth, H .,Steffens, E ., Vassiliev, A.High Field Permanent Sextopole Magnets for the ANKE ABSInt .Workshop on Polarized Sources and Targets (PST99), Erlangen,29 .9 . - 2 .10 .199920 .45 .0
IKP-99-12-22Büscher, M.First Resuite from Subthreshold K +-Production Measurements withANKE8'h Mt . Cont . on Hadron Spectroscopy (HADRON "99), Beijing,China, 24 . - 28 .8 .9920 .45 .0
IKP-99-12-23Büscher, M . für die ANKE-KollaborationStudy of subthreshold K+ -production at ANKEDPG Frühjahrstagung, Physik der Hadronen und Kerne, Freiburg,Germany, 22. - 26.3 .199920.45 .0
IKP-99-12-24Büscher, M.Mesonenproduktion in pp, pn und pA-Kollisionen an ANKEGemeinsames Seminar des DFG-Schwerpunkts ,,Untersuchung derhadronischen Struktur von Nukleonen mit elektromagnetischenSonden" und des SFB 443,Bad Honnef, Germany, 27 . - 28 .10 .99
20 .45 .0
IKP-99-12-25Cloth, P. ; Filges, D . and the members of the ZEUS Collaboration:Measurement of Dijet Photoproduction at High Transverse Energiesat HERAReport, DESY-99-057, May 199920 .48 .0
IKP-99-12-26Cloth, P. ; Enges, D . and the members of the ZEUS Geilaberation:Measurement of Diffractive Photoproduction of Vector Mesons atLarge Momentum Transfer at HERAReport, DESY-99-160, October 199920 .48 .0
IKP-99-12-27Cloth, P. ; Filges, D . and the members of the ZEUS Collaboration:Measurement of ,t, 7t, .fei/
Dependence of Forward-JetProduction at HERAReport, DESY-99-162, October 199920 .48 .0
IKP-99-12-28Cloth, P. ; Enges, D . and the members of the ZEUS Collaboration:Measurement of Inclusive Prompt Photon Photoproduction at HERAReport, DESY-99-161, October 199920 .48 .0
IKP-99-12-29Cloth, P. ; Filges, D . and the members of the ZEUS Collaboration:Search for Contact Interactions in Deep Inelastic e`p --i e*X
Scattering at HERAReport, DESY-99-058, May 199920 .48 .0
IKP-99-12-30Cloth, P. ; Enges, D . and the members of the ZEUS Collaboration:Measurement of High-Q2 Charged-Current e`p Deep InelasticScattering Cross Sections at HERAReport, DESY-99-059, July 199920 .48 .0
IKP-99-12-31Cloth, P. ; Filges, D . and the members of the ZEUS Collaboration:Measurement of the Spin-Density Matrix Elements in ExclusiveElectroproduction of p° Mesons at HERAReport, DESY-99-059, July 199920 .48 .0
229
IKP-99-12-32Cloth, P. ; Filges, D . and the mernbers of the ZEUS Collaboration:Measurement of Cl' Production and the Charm Contribution to F2 in
Deep Inelastic Scattering at HERAReport, DESY-99-059, July 199920 .48 .0
IKP-99-12-33Cloth, P. ; Filges, D . and the members of the ZEUS Collaboration:Angular and Current-Target Correlations in Deep InelasticScattering at HERAReport, DESY-99-063, May 199920 .48 .0
1KP-99-12-34Cloth, P. ; Filges, D . and the members of the ZEUS Collaboration:W Production and the Search for Events with an Isolated High-Energy Lepton and Missing Transverse Momentum at HERAReport, DESY-99-054, July 199920 .48 .0
IKP-99-12-35Daehnick, W., Doskow, J ., Haeberli, W., Lorentz, B ., Meyer, H . 0 .,Pancella, P. V. Pollock, R . E ., Quin, P., Rathmann, F., Rinckel, T.,Saha, S . K ., Schwartz, B ., Thörngren Engblom, P., Wise, T., vonPrzewoski, B ., für die PlNTEX-Kollaboration:Measurement of the Nuclear Polarization of Molecular Hydrogenformed by Recombination of Polarized Atoms in a Storage CellDPG-Frühjahrstagung, Physik der Hadronen und Keme, Freiburg,22. - 26 .3.199920.50 .0
1KP-99-12-36Dietrich, J.COSY beam : time structure, intensity and beam diagnosticsFirst Workshop of the JESSICA Collaboration, February 24, 1999,ESS 99-88-T20.30 .0
KP-99-12-37Dietrich, J . ; Keil, J . ; Mohos, 1.Control and Data Processing of the Distributed 500 MHzNarrowband Beam Position Monitor System of ELSAProc . PAC 99, New York, 29.3 .-2 .4 .199920.30.0
IKP-99-12-38Dietrich, J . ; Mohos, 1.Real-Time Betatron Time Measurement in the Acceleration Ramp atCOSY-JülichProc. 4a European Workshop en Beam Diagnostics andInstrumenation for Particle Accelerators (DIPAC 99)Chester, 199920.30.0
IKP-99-12-39Dietrich, J . ; Keil, J . ; Mohos, 1.Closed-Orbit Correction Using the New Beam Position MonitorElectronics of ELSA BonnProc . 4 'h European Workshop on Beam Diagnostics and
Instrumenation for Particle Accelerators (DIPAC 99)Chester, 199920.30.0
IKP-99-12-40Eßer, R.Cherenkov- und Szintiliationsdetektoren an ANKE5. COSY-FFE ArbeitstreffenInstitut für Kernphysik, FZ Jülich20 .45 .0
KP-99-12-41Eßer, R.First Experience with ANKE in COSYXXXVII International Winter Meeting en Nuclear PhysicsBonnie (Italien), 25 . - 29 .1 .199920.45.0
IKP-99-12-42Eßer, R.First Experience with ANKE in COSYUniversita degli Studi di MilanoRicerca Scientifica ed Educatione PermanenteSupplement) N . 114Edited by Ion20 .45 .0
IKP-99-12-43Enges, D . ; Ulimaier, H . ; Bräutigam, W.The Status of the European Spallation Neutron Source (ESS) R & DProgrammeCent. to Conferenee AccApp'99, Long Beach, Ca, USA, November14-18, 199920 .91 .0
IKP-99-12-44Filges, D . ; Goldenbaum, F. ; Neef, R.-D . ; Nünighoff, K .;Sterzenbach, G . ; Tietze, A . ; Tietze-Jaensch, H . for the NESSI andJESSICA Collaborations:ESS Target Development Experiments with up to 2 .5 GeV IneidentProton EnergyAccApp99, Nuclear Applications of Accelerator Technology, LongBeach, CA, USA, Nov . 14-18, 199920 .90 .0
IKP-99-12-45Filges, D . : Bräutigam, W. ; Enges, D . ; Ulimaier, H . for the ESS R&DCollaborations:The Status of the European Spallation Neutron Source (ESS) R&DProgrammeAccApp99, Nuclear Applications of Accelerator Technology, LongBeach, CA, USA, Nov. 14-18, 199920 .90 .0
IKP-99-12-46Goldenbaum, F. für die NESSI-Kollaboration:Validation of Spallation Physics Experiments up to 2 .5 GeV Ineide- tProton Energy - Neutron and Charged Particle Production onSpallation MaterialsThird Int . Workshop on Spallation Materials Technology, Santa Fe,New Mexico, April 29-May 4, 199920 .48.0
230
IKP-99-12-47Goldenbaum, F. ; Bohne, W.; Eades, J . ; v. Egidy, T. ; Figuera,Fuchs, H . ; Galin, J . ; Golubeva, Ye.S . ; Gulda, K . ; Hilscher, D .;lijinov, AS. ; Jahnke, U . ; Jastrzebski, J . ; Kurcewicz, W . ; Lott, B .;Morjean, M . ; Pausch, G . ; Pöghaire, A . ; Pienkowski, L . ; Poster, D .;Proschitzki, S . ; Quednau, B. ; Rossner, H . ; Schmid, S . ; Schmid, W .;Ziem, P.:Decay Modes Induced by Light Parteies (with Special Emphasis enAnti-Protons)Multifragmentation : Int. Workshop XXVII on Gross Properties ofNudel and Nudear Excitations, Hirschegg, Austria, Jan . 17-23,199920 .48 .0
IKP-99-12-48Grzonka, D.Program at COSYProc . of the Workshop on Future Directions in Quark NudearPhysics, Adelaide, Australia, 10 .-20 .3.1998, eds . A .W. Thomas andK . Tsushima, World Scientific, Singapore, 1999, p . 217ff20.45 .0
IKP-99-12-49Haidenbauer J.Meson Production in Nucleon-Nucleon CollisionsProceedings of the Workshop "On Future Directions in QuarkNuclear Physics", World Scientific, Singapore, 1999, p . 229-23820 .80 .0
IKP-99-12-50Haidenbauer J ., Hanhart C ., Speth J., Nakayama K ., Durso J .W.The Reaction pp-itppi° and the Validity of the OZI ruleProceedings of the 8th International 'Conference on the Structure ofBaryens "BARYON98", Bonn, Germany, September 1998, eds.D .W. Menze and B . Metsch, World Scientific, Singapore, 1999, p.583-58720 .80 .0
IKP-99-12-51Hanhart C ., Haidenbauer J ., Krehl 0 ., Speth J.Pion Production in Nucleon-Nucleon Collisions Proceedings of the8h' International 'Conference on the Structure ofBaryons"BARYON98", Bonn, Germany, September 1998, eds . D .W.Menze and B . Metsch, World Scientific, Singapore, 1999, p . 579-58220 .80 .0
IKP-99-12-52Heim Hencken K ., Trautmann D ., Baur G.Atomic Gorrections to the Electromagnetic Break-up of PioniumWorkshop on Hadronic Atoms, Bern, Switzerland, October 1999,appeared in the Miniproceedings HadAtom99, eds . J . Gasser, A.Rusetsky and J . Schacher, hep-ph/9911339, 199920.80 .0
IKP-99-12-53Hejny, V . für die TAPS- u . A2-KollaborationPhotoproduktion von Eta-Mesonen an leichten Kernen nahe derSchwelleDPG Frühjahrstagung, Physik der Hadronen und Kerne, Freiburg,Germany, 22 . - 26 .3.199920.50 .0
1KP-99-12-54Hejny, V. für die TAPS- u . A2-KollaborationPhotoproduction of Iight mesons - results from TAPS at MAMIWorkshop on Electromagnetic Radiation off Colliding HadronSystems : Dileptons & BremsstrahlungForschungszentrum Rossendorf, Germany, 16 . - 17 .4 .199920 .50 .0
IKP-99-12-55Hejny, V . für die TAPS- u . A2-KollaborationMeson photoproduction with TAPS at MAMI16th Students' Workshop on Electromagnetic lnteractionsBosen(Saar), Germany, 5 . - 10 .9 .199920 .50 .0
IKP-99-12-56Junghans, H . für die ANKE-KollaborationProcedure of K+-identification at ANKEDPG Frühjahrstagung, Physik der Hadronen und Kerne, Freiburg,Germany, 22. - 26 .3 .199920.45 .0
IKP-99-12-57Kliczewski, S . et al.Meson Production Study Using the GEM DetectorFew Body Sys . Supp (1999), in press20 .45 .0
IKP-99-12-58Koptev, V.,
Kovalev, A.,
Kravtsov, P.,
Mikirtytchiants, M .,Nekipelov, M ., Rathmann, F., Seyfarth, H ., Vassiliev, A.:lnvestigation of the Atomic Hydrogen Beam with a Two-dimensionalMultiwire MonitorInt . Workshop on Polarized Sources and Targets (PST99),Erlangen, 29 .9 . - 2 .10 .199920 .45 .0
IKP-99-12-59Krewald S.Pion-Nucleon Scattering and the Structure of the NucleonProceedings of the Workshop on Hadron Spectroscopy, Frascati,ltaly, Frascati Phys . Ser., Vol . XV, 211-21520 .80 .0
IKP-99-12-60Lehrach, A . ; Bechstedt, U . ; Dietrich, J . ; Gebel, R . ; Henn, K. ; Maier,R. ; Prasuhn, D . ; Schnase, A . ; Stassen, R . ; Stockhorst, H . ; Tölle, R.Experience with polarized proton acceleration at GOSYPolarized Protons at High Energies - Accelerator Challenges andPhysics Opportunities, Workshop, 17 .-20 . May 1999, DESY-Hamburg20.30.0
IKP-99-12-61Lehrach, A . ; Bechstedt, U . ; Dietrich, J . ; Gebel, R. ; Henn, K . ; Maier,R . ; Prasuhn, D. ; Schnase, A . ; Stassen, R . ; Stockhorst, H . ; Tölle, R.Acceleration of the Polarized Proton Beam in the CoolerSynchrotron GOSYProc . PAG 99, March 29'h -April 2''h , 1999, New York20 .30 .0
231
IKP-99-12-62Lieder, R .M.The TMR Network Project "Development of Gamma-Ray TrackingDetectors"Proc . EUROBALL Workshop "Physics and Perspective using theEUROBALL IV Spectrometer", Strasbourg (1999), ed . G . Ducheneand M .M. Aleonard20 .10 .0
IKP-99-12-63Lieder, R .M., Rzaca-Urban, T., Brands, H ., Gast, W., Jäger, KM .,Mihailescu, L, Pytel, Z., Urban, W ., Morek, T., Droste, Chr., Chmel,S ., Bazzacco, D ., Falconi, G ., Menegazzo, R ., Lunardi, S ., Rossi-Alvarez, C ., de Angelis, G ., Famea, E ., Gadea, A ., Napolie, D.R .,Podolyak, Z.Investigation of Magnetic Rotational Bands in 142Gd withEUROBALLProc. EUROBALL Workshop "Physics and Perspectives using theEUROBALL IV Spectrometer, Strasbourg (1999), ed. G . Ducheneand M .M. Aleonard20 .10 .0
1KP-99-12-64Lorentz, B. ; Bechstedt, U . ; Dietrich, J . ; Nenn, K . ; Lehrach, A . ; Maier,R . ; Prasuhn, D . ; Schnase, A . ; Schneider, H . ; Stassen, R .;Stockhorst, H . ; Töne, R.Stochastic cooling and extraction at COSYSTORI 99, Bloomington, USA20 .30 .0
IKP-99-12-65Machner H . and Haidenbauer, J.Meson Production Close to ThresholdProc. MENU99, ftN Newsietters (in press)20 .45 .0, 20 .80 .0
IKP-99-12-66Maier, R ., Martin, S . A ., Prasuhn, D ., Stein, H . J ., Witt, J .-D.Electron Cooling in COSYProc. 4 Workshop on Medium Energy Electron Cooling,Dubna 1998, Editor 1 . Meshkov, ISBN 5-85165-530-5 (1999)258
IKP-99-12-67Meißner Ulf-G.Pion-Nucleon Scattering and Isospin ViolationWorkshop on Future Directions in Ouark-Nuclear Physics, Adelaide,Australia, March 1998, appeared in "Future Directions in Quark-Nuclear Physics," eds . A .W. Thomas and K . Tsushima, WoridScientific, 199920 .80 .0
1KP-99-12-68Meißner Ulf-G.Chiral dynamics : Status and PerspectivesEffective Field Theory Approaches to Pion Production in Proton-Proton Collisions8th International Conference on the Structure of Baryons (Baryons98), Bonn, Germany, September 1998, appeared in Baryons `98,eds . W. Menze and B.Ch . Metsch, Worid Scientific, 199920 .80 .0
IKP-99-12-69Meißner UWG.Pion-Kaon ScatteWorkshop on in dron i - Atoms, Bern, Switzerland, October 1999,a a in the 1 sm ?.edings HadAtom99, eds . J . Gasser, A.Rusetsky and J . Schacher, hep-ph/9911339, 199920 .80 .0
iKP-99-12-70Mihailescu, L ., Gast, W., Lieder, R .M ., Rossewij, M.On-Line Pulse Shape Analysis Algorithms for Tracking DetectorsProc, EUROBALL Workshop "Physics and Perspective using theEUROBALL IV Spectrometer", Strasbourg (1999), ed . G . Ducheneand M.M. Aleonard20.10.0
KP-99-12-71Moskal, R.tj" Meson Production in the pp ppn Reaction near Thresholdinterner Bericht, JÜL-3685, 199920 .50 .0
IKP-99-12-72Nikolaev N .N.ntrinsic k-perpendicular in the Pomeron"Monte Carlo Generators for HERA physics, DESY, 1999, ed . H.Jung, pp 377-38120 .80 .0
KP-99-12-73Prasuhn, D . ; Dietrich, J . ; Maier, R . ; Stassen, R . ; Stein, J .;Stockhorst, H . ; Witt, J.Electron and stochastic Cooling at COSY JülichECOOL 9920 .30 .0
IKP-99-12-74Sistemich, K.The ANKE Spectrometer at COSY-Jülich and Studies of theSubthreshold ProductionPANIC 99, Uppsala, 10 . - 16 .6 .199920 .45 .0
KP-99-12-75Smyrski, J . (together with the COSY-11 Collaboration)Near-Threshold Meson Production in Proton-Proton CollisionsFZJ-IKP(I)-1999-120 .50 .0
IKP-99-12-76Strokowsky, E .A. et ai .(SPES 4zc-Coliaboration)Study of Delta and Roper Resonance Excitation
Light NucleiInduced ReactionsFew Body Systems Suppi . 10 (1999) 495-49820 .45 .0
1KP-99-12-77Trautmann D ., Halabuka Z ., Heim T., Hencken K., Meier H ., Baur G.Excitation and lonization of Exotic and Non-exotic Atoms in Heavy-Ion CollisionsCP475, Applications of Accelerators in Research and lndustry, eds.J.L . Duggan and I .L. Morgan, The American Institute of Physics 1-56396-825-8/199920 .80 .0
1KP-99-12-78Zychor,Proton induced reactions at intemal targets at COSY-JülichXXVI Mazurian Lakes School, September20 .45 .0
232
invited Talks
1KP-99-21-1Baur G.Double Giant Dipole Resonance : A Strongly Damped CollectiveMotionInternational Workshop on Double Giant Resonances in Nuclei,Trento, Italy, 10.-21 .5 .199920 .80 .0
IKP-99-21-2Baur G.Photon-Photon and Photon-Hadron interactions at RelativisticHeavy Ion Coiliders,,intemational School of Nuclear Physics : Heavy Ion Collisions fromNuclear to Quark Matter",Erice, Sich', 17.-25 .9.199920 .80 .0
1KP-99-21-3Baur G.Mechanisms of Direct Breakup ReactionsRCNP-TMU Symposium on Spins in Nuclear and HadronicReactions, Tokyo, Japan, 26 .-28 .10 .199920 .80 .0
1KP-99-21-4Bojowald, J .:Nuclear Electronics at GEM : Statistics of Pulse-Amplitudes andPulse-Intervals, presented at B .A .R .C . Bombay, Dec . 199820 .45 .0
IKP-99-21-5Borchert, G . L.X-ray spectroscopy in pionic atoms and the muon-neutrino mass,HEPITU,Tiflis, 11 .8 .9920 .50 .0
IKP-99-21-6Borge, W ., Cassing, W ., Hartmann, M ., Hermes, T., Jarczyk, L .,Kamys, B., Kistryn, Koch, H . R ., Kulessa, P ., Maier, R .,Matoba, M., Ohm, H ., Pfeiffer, J ., Prasuhn, D ., Pysz, K., Rudy, Z .,Schult, 0 ., Ströher, H., Strzalkowski, A., Uozumi, Y., Zychor, 1 .,Measurements of the Lifetimes of Heavy Hypernuclei at COSY-JülichSeminarvortrag, National-Institut für Kernphysik, Padua, 2 .6.199920 .405 .0
IKP-99-21-7Büttiker P.Pion-Nucleon Scattering inside the Mandeistam PlaneEighth International Symposium on Meson-Nucleon Physics andthe Structure of the Nucleon, Zuoz, Switzerland, August 199920 .80 .0
IKP-99-21-8Büttiker P.Pion-Pion Scattering in Chiral Perturbation and Dispersion RelationTheoriesSymposium on Frontiers of Fundamental Physics, Hyderabad,India, January 199920 .80 .0
IKP-99-21-9Elster Ch.Three Body States : An Approach without Angular MomentumDecompositionSymposium "Current Topics in the Field of Light Nudel",Kracow, Poland, 21 .-25 .6 .199920 .80 .0
IKP-99-21-10Elster Ch.Three Body Stetes : An Approach without Partial WavesGordon Research Conterence "Dynamics of Simple Systems inChemistry and Physics", Newport News, USA, 11 .-16 .7 .199920 .80.01KP-99-21-11Elster Ch.Few Body Caleulations : An Approach without Partial Waves
Workshop "The Nuclear Interaction : Modem Developments",Trento, Italy, 7 .8 .199920.80.0
IKP-99-21-12Eßer, R.Physics with ANKE and other Facilities at COSY-JülichHigh Energy Physics Institute, Tbilisi State University, 13 .10 .199920 .45 .0
IKP-99-21-13Fiiges, D .:Transmutation von langlebigen radioaktiven Abfällen ausKernreaktorenPhysikalisches Kolloquium, Ruhr-Universität Bochum, 11 .1 .199920 .48 .0
IKP-99-21-14Fiiges, D . ; Schaaf, H . ; Broome, T .:Radiation Shielding and Protection of the European SpallationNeutron Source (ESS)Ninth Int . Conference on Radiation Shielding (ICRS-9), JapanAtomic Energy Research Instituts (JAERI), Tsukuba, Japan,17 . - 22 .10 .199920 .90 .0
1KP-99-21-15Fiiges, D .:Spallation Physics Experiments - Rast and FutureSpecial Seminar SNS-Project, ORNL, Oak Ridge, USA, 21 .11 .199920 .90 .0
IKP-99-21-16Gast, W.Deveiopment of Gamma-Ray Tracking DetectorsKolloquiumsvortrag im Inst. of Nuci . Res . and Nuci . Energy,Bulgarian Academy of Sciences, Sofia, Bulgaria, 10 .11 .199920 .10 .0IKP-99-21-17Gellas G.N>D Transition Form Factors in Chiral Effective TheoriesH2 Collaboration Meeting, Mainz, Germany, July 199920 .80 .0
IKP-99-21-18Gillitzer, A.Observation of well-resolved ls and 2p tti states in Pb by highresolution (d,3 He) spectroscopyInstitut de Physique Nuciöaire Orsay, 11 .10 .199920 .50 .0
IKP-99-21-19Goldenbaum, F . ; Chevallier, M . ; Cohen, C . ; Dauvergne, D . ; Delta-Negra, S . ; Galin, J . ; Jacquet, D . ; Kirsch, R . ; Lienard, E . ; Lott, B .;Morjean, M . ; Pöghaire, A. ; Pörier, Y. ; Poizat, J .C . ; Prevot, G .;Remillieux, J . ; Schmaus, D. ; Toulernonde, M .:Fission Lifetimes as a Function of E* Applying the BlockingTechniqueXlith Colloque GANIL, Seignosse le Penon, France, 17 . - 21 .5 9920 .48 .0
233
!KP-99-21-20Grzonka, D.Strangeness Experiments at COSYAPCTP Workshop on Strangeness Nuclear Physics (SNP '99),Seoul, Republic of Korea, 19 . - 22 .2.199920 .45 .0
IKP-99-21-21Hemmert T.A.Chiral Symmetry and the N-Delta TransitionELSA Schwerpunkttreffen, Bad Honnef, Germany,4.2 .199920 .80 .0
!KP-99-21-22Hemmert T.R.Chiral Effective Theories in the Single Nucleon SectorGordon Conference on QCD, Newport News, USA, 28.7 .199920 .80 .0
!KP-99-21-23Hemmert T.A.The Chiral Structure of HadronsSantorini 99 Conference on Electromagnetic lnteractionsSantorini, Italy, 6.10 .199920 .80 .0
1KP-99-21-24Hennebach, M.Curved Cherenkov Detectors for ANKE's Negative SideHigh Energy Physics Institute, Tbilisi State University13 .10 .199920 .45 .0
IKP-99-21-25Hesselbarth, D.Offline Evaluation of Associated Strangeness Data at COSY-TOFXVth Partielee and Nuclei International Conference (PANIC 99),Uppsala/Schweden, 10 .-16 .6 .199920 .45 .0
1KP-99-21-26Junghans, H.Subthreshold K +-Production at ANKE- First ResultsSymposium on Ten Years of Jülich-Cracow Collaboration at COSY,Jagellonian University of Cracow, Poland, 24 . - 26 .9 .199920 .45 .0
IKP-99-21-27Kamerdzhiev S.There is No Missing lsoscalar Monopole Strenght in 58NiInt . Workshop "Collective Excitations in Nuclei and other FiniteFermi-Systems, Dubna, Russia, 14 .-24.6 .199920 .80 .0
iKP-99-21-28Kilian, K.Meson Production of Low EnergyInt . Summer School : Particle Production Spanning MeV and TeVEnergies, Nijmegen, 8 .-20 .8 .199920 .45 .0
!KP-99-21-29Kilian, K.Optimal Tools for Experlmental PhysicsSymposium on Ten Years of Cracow-Jülich Collaboration at COSY,Krakau, 24 .-25.9 .199920 .45 .0
KP-99-21-30Krehl O.Pion-Nucleon-ScatteringMindere University, Adelaide, Australia, 26 .2 .199920 .80.0
IKP-99-21-31Krewald S.Pion-nucleon Sattering and the Structure of the Nucleon,Workshop on Hadron Spectroscopy, Frascati, Italy,8 . - 12 .3.199920 .80 .0
iKP-99-21-32Krewald S.Spin Observables -What can we leam from this Experlmental Tool?Symposium on Ten Years of Cracow-Jülich Collaboration at COSY,Cracow, Poland, 24. - 25 .9 .199920 .80 .0
1KP-99-21-33Krewald S.Modelling the Spectral FunctionsWorkshop on the Low-Energy Electroweak Sea-quark Structure ofthe Nucleon, University of Connecticut, Storrs, USA, 11 . - 13 .11 .9920 .80.0
IKP-99-21-34Kuhlmann, E.Bremsstrahlung Experiments at COSY-TOFInt . Workshop on Electromagnetic Radiation of Colliding HadronSystems : Dileptons and Bremsstrahlung, Rossendorf/Dresden,16 . - 17.4 .199920 .45 .0
IKP-99-21-35Lieder, R.Study of Magnetic Rotation in 142Gd with EUROBALLWorkshop Medium Mass Nuclei, FZ Rossendorf, 25 . - 26.2 .199920 .10 .0
1KP-99-21-36Lieder, R.M.Recent Developments in y-Ray Trackinglnvited Talk at the Spring Symp . of the Niets Bohr Institute,University of Copenhagen, Copenhagen, Denmark, 6 .5 .199920 .10 .0
IKP-99-21-37Lieder, R.M.Gamma Detector Arrays in Present and Future Nuclear StructureResearchKolloquiumsvortrag im Inst. of Nucl . Res . and Nucl . Energy,Buigarian Academy of Sciences, Sofia, Bulgaria, 9 .11 .199920.10 .0
1KP-99-21-38Machner, H.Pion and Eta Production in pp and pd Interactions at COSYSeminar, George Washington Univ ., Washington DC, 7 .9 .199920.45 .0
IKP-99-21-39Machner, H.Pion and Eta Production in Proton Induced Reactions, Study ofIsospin Symmetry BreakingSeminar Jefferson Lab., Newport Virg ., 10 .9.199920.45 .0
IKP-99-21-40Machner, H.Present Interests of GEMGEM-Kollaborationstreffen, Bombay, 24 .-26 .12 .199920 .45 .0
IKP-99-21-41Maier, R.COSY, Performance and PerspeotivesBrookhaven National Laboratory, USA, 15 .7 .199920 .30 .0
234
IKP-99-21-42Maier, R.Das Cooler Synchrotron COSY in JülichGraduiertenkolleg der TU Darmstadt, 3 .11 .1999 Bad Honnef2020 .0
KP-99-21-43Maier, R.Beschleunigerphysikalische Arbeiten am Kühlersynchrotron COSYGraduiertenkolleg der TU Darmstadt, 13 .12 .199920 .30 .0
IKP-99-21-44Meißner Ulf-G.Lectures on Chirai Perturbation TheoryXth Jorge Andre Swieca Scheel on Nuclear Physics, Sao Paulo,Brasii, January 1999,20 .80 .0
1KP-99-21-45Meißner UWG.sospin Violation in the Two-Nucleon System
INT Workshop on Nuclear Physics with Effective Field Theory,Seattle, USA, February 199920 .80 .0
IKP-99-21-46Meißner Ulf-G.Isospin Violation in the NN SystemInternational Workshop en Nucleon-Nucleon Interaction, BadHonnef, Germany, May 199920 .80 .0
IKP-99-21-47Meißner Ulf-G.Baryon Formfactors : Model-independent ResultsWorkshop on "The Structure of the Nucleon" (Nucleon '99),Frascati, Italy, June 199920 .80 .0
1KP-99-21-48Meißner Ulf-G.Chirai Dynamics in the Two-Nucleon SystemWorkshop on "The Nuclear Interaction : Modern Developments,"ECT*, Trento, Italy, June 199920 .80 .0
1KP-99-21-49Meißner Ulf-G.Effective Field Theory for the Two-Nucleon SystemIsospin ViolationEighth International Symposium on Meson-Nucleon Physics andthe Structure of the Nucleon, Zuoz, Switzerland,August 199920 .80 .0
IKP-99-21-50Meißner Ulf-G.Chiral QCD Dynamics: Recent ResultsInternational Workshop on Hadron Physics, Coimbra, Portugal,September 199920 .80 .0
1KP-99-21-51Meißner Ulf-G.Chirai Effective Field Theories21th International School on Nuclear Physics, Erbe, Sicily,September 199920 .80 .0
1KP-99-21-52Meißner Ulf-G.Pion-Kaon ScatteringWorkshop on Hadronic Atoms HadAtom99',Bern, Switzerland, October 199920 .80 .0
IKP-99-21-53Meißner Ulf-G.Hadronic PhysicsThird Workshop on Physics and Detectors for DAPHNE, Frascati,Italy, November 199920 .80 .0
IKP -99-21-54Morsch, H .P.Nucleon Resonance Excitations in Hadron ScatteringSeminar KVI Groningen, 30 .11 .199920 .45 .0
IKP-99-21-55Nikolaev N .N.Spin Dependence of Diffractive DIS7th international Workshop on Deep Inelastic Scafering and QCD(DIS99), Zeuthen, Germany, 19 . - 23 .4 .199920.80.0
IKP-99-21-56Nikolaev N .N.Spin Dependence of Diffractive Vector Meson Production6th 1NT/Jeffersan Lab . Workshop on Exclusive and SemiexclusiveProcesses at High Momentum Transfer, Newport News, USA, 19 .-23.5 .199920.80 .0
IKP-99-21-57Nikolaev N .N.Diffractive Scattering in Deep Inelastic ProcessesSpin Effects in Diffractive Vector Meson Production in DISInternational Conference on Elastic and Diffractive Scattering(Vllith Bleis Workshop), Protvino, Russia, 28 .6 . - 2 .7 . 199920 .80 .0
IKP-99-21-58Nikolaev N .N.Diffractive DIS : Status and ProblemsWorkshop on Diffraction at Colliders, Dubna, Russia3 . - 6 .7 .199920 .80 .0
1KP-99-21-59Nikolaev N .N.Helicity Flip in Diffractive DIS19th International Symposium on Multiparticle Dynamics (ISMD99), Providence, USA, 9 . - 13 .8 .199920 .80 .0
1KP-99-21-60Oelert, W . (fix the COSY-11-Collaboration at COSY/Jülich)Auf dem Weg zum Antiwasserstoff in RuheArbeitstreffen Mittelenergiephysik, Endingen, 4 . - 8 .10 .199920 .45 .0
IKP-99-21-61Ohm, H.Determination of the lifetime of heavy A -hypemuciei at COSYJülichSTORI99, Physics with storage rings, Bloomington, Indiana, USA,12 . - 16 .9.1999
235
1KP-99-21-62Ohm, H.Die Messung der Lebensdauer schwerer Hyperkerne an COSYArbeitstreffen "Struktur stark wechselwirkender Teilchen",Endingen, 4 . - 8 .10 .1999
IKP-99-21-63Schäfer W.Unitary Driven Spin Effects in Deep Inelastic ScatteringState University New York, Stony Brook, NY, USA, 1 .3 199920 .80 .0
KP-99-21-64Schäfer W.Nonperturbative Effects in the Proton SeaNT/JLAB Workshop on Exclusive and Semiexclusive Processes atHigh Momentum Transfer, Jefferson Lab ., Newport News, USA,20 .5 .199920 .80 .0
KP-99-21-65Schnase, A.lntroduction to Proton Accelerator COSY and Overview of digitalsignal generation for COSY RF systemsKEK Tanashi, 1 .11 .1999, Japan20 .30 .0
1KP-99-21-66Schnase, A.Low-level RF synthesis for Proof-of-Principle FFAGWorkshop on Very Rapid Cycling Acceleration with FFAGSynchrotronsKEK, Tsukuba, Japan, 6 . - 8 .12 .199920 .30 .0
KP-99-21-67Schnase, A.COSY and its digital Iowa level RF-systemsKEK, Tsukuba, Japan, 9 .12 .199920.30.0
KP-99-21-68Schult, O.Lifetime Measurements of Hypernuclei at COSYInternational Symposium on Nuciear Electro-Weak Spectroscopyfor Symmetries and Electro-Weak Nuebar Proeesses (NEWS99)Osaka University, Osaka, Japan 11 .3.9920 .45 .0
1KP-99-21-69Schult, O.On the Mime of heavy hypernucleiSeminarvortrag im Dipartimento di Fisica, Universitä di Firenze,4.11 .9920 .45 .0
IKP-99-21-70Speth J.Effective Lagrangian and Meson-Nucleon ScatteringECT Workshop "Hadron-Hadron Interactions", Trento, 1taly,6.7 .199920 .80 .0
1KP-99-21-71Speth J.Meson-Produktion bei hadronischen Reaktionen an der SchwelleWorkshop "Mesonproduktion an Erzeugungsschwelle", BadHonnef, Germany, 27.10 .199920 .80 .0
1KP-99-21-72Speth J.Strangeness Production at StrangenessSymposium in Honour of Carl Dover, BNL Brookhaven, USA, 10 .-12 .12 .199920 .80 .0
1KP-99-21-73Ströher, H.Die innere Struktur des NukleonsAntrittsvorlesung Universität zu Köln, 2 .2 .199920 .50 .0
1KP-99-21-74Ströher, H.Polarization Experiments from Mainz and BonnThe US-Japan Joint Workshop on Probing Hadron Structure withPolarized Photons, Hawaii-IMIN International East-WestConference Center (EWG)University of Hawaii, Honolulu, Hawaii, 22 . - 25 .2 .199920 .50 .0
1KP-99-21-75Ströher, H.Mittelenergie-Physik mit elektromagnetischen und hadronischenProbenPhysikalisches Kolloquium Universität Göttingen, 17 .5 .9920 .50 .0
1KP-99-21-76Ströher, H.Threshold Meson Production in Photo- and Proton-nuclearreactionsKVI Groningen, 8 .6 .9920 .50 .0
IKP-99-21-77Ströher, H.Electromagnetic and hadronic meson production near thresholdWorkshop on ,,Leptons and Hadrons as Complementary Probes ofStreng QCDJülich, 18.6 .9920.50 .0
IKP-99-21-78Ströher, H.Hadronenphysik mit elektromagnetischen und hadronischenProbenGraduiertenkolleg ,,Schwerionenphysik", Universität Gießen, 8 .7 .9920 .50 .0
IKP-99-21-79Ströher, H.First Results on Strangeness Production from the ANKE FacilitySTORI99, Bloomington, Indiana, 12 . - 16 .9.199920 .45 .0
IKP-99-21-80Ströher, H.COSY Experiments in the Near FutureSymposium on Ten Years of Jülich-Cracow Collaboration at COSY,Jagellonian University of Cracow, Poland, 24. - 26 .9 .199920 .45 .0
IKP-99-21-81Ströher, H.Hadronenphysik mit Photonen und ProtonenInstitutsseminar, Forschungszentrum Rossendorf, 13 .12 .9920 .50.0
1KP-99-21-82Ströher, H.Zukunft an ANKECANU-Meeting, Bad Honnef, 20 .12 .199920.50.0tKP-99-21-83Wirth, S.Associated Strangeness Production at COSY-TOFSTORI99, Bloomington/IN, USA, 12 .-16.9 .199920.45 .0
236
Conference Contributions
IKP-99-22-1Baur G.Another Exotic Relativistic Atom : AntihydrogenWorkshop Hadronic Atoms 1999, Bern, Switzerland, 14 .-15 .10 .199920 .80 .0
IKP-99-22-2Baur G.New Possibilities for Coulomb DissociationPIKEN, Tokyo, Japan, 29.101 99920 .80 .0
IKP-99-22-3Baur G.Photon-Photon and Photon-Nucieus Interactions in Relativisticheavy Ion CollidersRCNP, Osaka, Japan, 4 .11 .199920.80 .0
IKP-99-22-4Brands, H.Untersuchung von Ge-Detektor Pulsformen und digitaleSignalverarbeitung für HaibleiterdetektorsignaleDipl .Koll . im ISKP der Uni Bonn, 17 .3 .199920 .10 .0
IKP-99-22-5Brinkmann, K .-Th.Schwellennahe Plenenproduktion am Flugzeitspektrometer TOFVerhandlungen der DPG, Freiburg, 20 . - 26 .3 .199920 .45 .0
IKP-99-22-6Calen, H. (for the PROMICE/WASA Collaboration atCELSIUS/Uppsala)The WASA Detector at CELISUSXVth Particles and Nuclei Int . Conf, PANIC, Uppsala, Sweden, 10 .-16 .6 .199920 .45 .0
IKP-99-22-7Calen, H. (fix the WASA-CELSIUS Kollaboration atCELSIUS/UppsalaWASA Detector Rare Pion and Eta DecaysSTORI `99, Bloomington, IN, USA, 12 .-16 .9 .199920.45 .0
IKP-99-22-8Clement, H . (for the PROIVIICEANASA Collaboration atCELSIUS/Uppsala)
Production in pp Cellisions Close to ThresholdXVth Particles and Nudel Inf . Conf ., PANIC, Uppsala, Sweden, 10 .-16 .6 .199920 .45 .0
IKP-99-22-9Dietrich, J.Strahldiagnose am Synchrotron mit externer StahlanregungForschungszentrum Rossendorf, Institut für Kemphysik, 25 .1 .199920 .30 .0
IKP-99-22-10Dietrich, J.Dynamische Tune-Messung an COSYWinterseminar des Instituts für Angewandte Physik der J . W.Goethe-Univ . Frankfurt/Main, Riezlem, 28 .2 .-6 .3 .199920.30,0
!KP-99-22-11Dietrich, J.Strahldiagnose am Kühler-Synchrotron COSY-JülichUniversität Leipzig, Fakultät für Physik und Geowissenschaften,17 .3 .199920 .30 .0
IKP-99-22-12Enke, M .; Filges, D . ; Galin, J . ; Goldenbaum, F . ; Herbach, C .;Hilscher, D . ; Jahnke, U . ; Letourneau, A . ; Lott, B . ; Neef, RD .;Nünighoff, K . ; Patois, Y. ; Paul, N . ; Peghaire, A . ; Pienkowski, L .;Schaal, H . ; Schräder, W .N . ; Tietze, A . ; Töke, I . für die NESSI-Kollaboration:Neutron (and Charged Particle) Production feie GeV Proton-NucleusSpaltaffen ReactionsDPG-Frühjahrstagung, Physik der Hadronen und Kerne, Freiburg,22 .-26.3 .199920 .90 .0
1KP-99-22-13Erhardt, A.2n-Produktion im NN-Stoß an COSY-TOFVerhandlungen der DPG, Freiburg, 20 .-26 .3 .199920 .45 .0
!KP-99-22-14Fanara, C . ; Filges, D . ; Geyer, R . ; Kilian, K . ; Nünighoff, K . ; Schmitz,T.:Entwicklung eines sehr leichten Spur-DetektorsDPG-Frühjahrstagung, Physik der Hadronen und Keme, Freiburg,22.-26 .3 .199920 .48.0
IKP-99-22-15Felden, O.Das AtomstrahltargetEDDA Koliaborationstreffen, Hamburg, 3 . - 5 .3 .199920 .38 .0
IKP-99-22-16Felden, O.Optimierung des polarisierten QuellenstromsEDDA Koliaborationstreffen, Hamburg, 3 . - 5 .3 .199920 .38 .0
IKP-99-22-17Feiden, O. (for the EDDA Kollaboration)Das polarisierte Atomstrahltarget für das EDDA-Experiment anCOSYDPG-Tagung, Freiburg, 23 . - 25 .3.199920 .38 .0
IKP-99-22-18Felden, O.The polarized Beam at COSY2nd int. Workshop en N-N-Interaction, Bad Honnef, 31 .5 . - 1 .6 .199920 .38 .0
1KP-99-22-19Feiden, O.Das AtomstrahltargetEDDA-Kollaborationstreffen, Bad Honnef, 21 . - 22 .12 .199920 .38 .0
237
KP-99-22-20Fettes N.Pion-Nukleon Scattering in Chiral Perturbation TheoryDPG-Frühjahrstagung, Freiburg, Germany, 22 .3 .199920 .80 .0
IKP-99-22-21Fettes N.Field Theory Approach to 1sospin Violation in Low-Energy Pion-Nueleon ScatteringWorkshop "MENU99", Zuoz, Switzerland, 17 .8 .199920 .80 .0
IKP-99-22-22Fettes N.sospin Violation in Low-Energy Pion-Nucleon ScatteringInternational School on Nuclear Physics ; 21 st Course:"Electromagnetic Probes and the Structure of Hadrons and Nuclei",Erice, Sicily, 21 .9 .199920.80.0
IKP-99-22-23Filges, D .:Sallation Physics6 ESS General Meeting, Ancona, Italy, 20 . - 23 .9 .199920.90.0
KP-99-22-24Gast, W ., Brands, H ., Georgiev, A., Jäger, H .M ., Lieder, R .M.,Mihailescu, L.,Rossewij, MJ ., Stein, J.mplementation of the Pulse Proccesing Analog to Digital Converterinto a PC enviromentVerhandlungen der DPG, Freiburg, 20 . - 26 .3 .199920 .10 .0, 20 .45 .0
IKP-99-22-25Gillitzer, A.Tiefgebundene pionische Zustände in BleiArbeitstreffen ”Struktur stark wechselwirkender Teilchen",Endingen, 4 . - 8 .10 .199920 .50 .0
IKP-99-22-26Goldenbaum, F.:Validation of Hadron - Nucleus Transport Models6 th ESS General Meeting, Ancona, Italy, 20 . - 23 .9.199920 .48 .0
KP-99-22-27Grzonka, D.Strangeness Experiments at COSYAPCTP Workshop on Strangeness Nuclear Physics '99, Seoul,Korea, 19 . - 22 .2 .199920 .45 .0
IKP-99-22-28Haidenbauer J.Meson-Exchange model for the YN InteractionXVth Particles and Nuclei Conference, Uppsala, Sweden,10 . - 16 .6 .199920 .80 .0
IKP-99-22-29Haidenbauer J.The Reactions pp-epAK'' and pp-;ipE°K* near their ThresholdsSTORI99, Bloomington, Indiana, USA12 . - 16.9 .199920 .80 .0
IKP-99-22-30Hemmert T.R.Chiral Effective Theories and Hadron Form FactorsUniversität Bochum, Germany, 22 .1 .199920 .80 .0
IKP-99-22-31Hemmert T.R.Die Rolle der Delta-Resonanz in der Pion PhotoproduktionMuonen-Einfang und der pseudoskalare Formfaktor des NukleonsDPG-Frühjahrstagung, Freiburg, Germany, 23 .3 .199920 .80 .0
IKP-99-22-32Hemmert T.R.Delta (1232) in chiraler StärungsrechnungGraduiertenkolleg, Mainz, Germany, 3 .11 .199920 .80 .0
IKP-99-22-33Hemmert T .R.Chirale effektive Theorien und die Strangeness im NukleonUniversität Heidelberg, Germany, 13 .12 .199920 .80 .0
IKP-99-22-34Ilieva, I.Silicon strip detectors for beam adjustment at GEM (COSY)Verhandlungen der DPG, Freiburg, 20 . - 26 .3.199920.45 .0
IKP-99-22-35Jochmann, M . (for the COSY-11 Collaboration at COSY/Jülich)In CEMOS-Technologie integrierte Diskriminatoren für schnelleSzintillationszähler an COSY-11Verhandlungen der DPG ,Freiburg, 20 . - 26 .3 .199920 .45 .0
IKP-99-22-36Khoukaz, A . (for the COSY-11 Collaboration at COSY/Jülich)Near Threshold of -g,n' and Charged Kaon Pairs in Proton-ProtonCollisionsXVth Particles and Nuclei Int . Conf . PANIC, Uppsala, Sweden,10 . - 16 .9 .199920 .45 .0
IKP-99-22-37Kilian, K.Experiments with COSY3 Conf . and Workshop on Cyclotrons and Applications, Kairo,Agypten, 6 . - 10 .2 .199920 .45 .0
IKP-99-22-38Kilian, K.Threshold Hadron Production at COSYRCNP Osaka Irrt . Symp. on Nuclear Electro-Weak Spectroscopy(NEWS 99), Osaka University, Japan,9 . - 12 .3 .199920.45 .0
IKP-99-22-39Kilian, K.Double Strangeness Production with Hypemuclei at RestWorkshop on Future Perspectives of Physics with CooledAntiproton Beams, Rauischholzhausen, B. - 9 .4 .199920 .50 .0
IKP-99-22-40Klimala, W.Upgrade of a magnetic spectrograph to 3 times higher magneticrigidityVerhandlungen der DPG, Freiburg, 20 . - 26 .3 .199920 .45 .0
IKP-99-22-41Krehl 0.Extended Coupled Channel Model for ltN ScatteringDPG-Frühjahrstagung, Freiburg, Germany,22 .3 .199920 .80 .0IKP-99-22-42Krehl 0.Influenee of the Hyperon-Nucleon lnteraction on the AssociatedStrangeness ProduetionDPG-Frühjahrstagung, Freiburg, Germany, 23 .3 .199920 .80 .0
1KP-99-21-43Kulessa, P.Determination of the A hyperon lifetime in heavy hypemucleiXr)O<Vll Intern . Winter Meeting on Nuclear Physics, Bormio, Italy,25 . - 30 .1 .1999
238
IKP-99-22-44Lieder, R .M.Study of Shape Coexistence in Nuclei around 142Gd withEUROBALLVerhandlungen der DPG, Freiburg, 20 . - 26 .3 .199920 .10 .0
1KP-99-22-45Lieder, R .M.Investigation of Magnetic Rotational Bands in 142Gd withEUROBALLEUROBALL Workshop, Strasbourg, France, 27.11 .199920.10 .0
1KP-99-22-46Lieder, R .M.The TMR Network Project ,,Development of y-Ray TrackingDetectors'EUROBALL Workshop, Strasbourg, France, 28.11 .199920 .10 .0
IKP-99-22-47Lister, T ., Quentmaier, C ., Wolke, M.Die Reaktion pp--›ppK+X im Massenbereich der K +K'ProduktionsschwelleVerhandlungen der DPG ,Freiburg, 20 .-26,3 .199920 .50 .0
IKP-99-22-48Lorentz, B.Stochastic Cooling and Extraction at 00SYSTORI 99, Bloomington, IN, USA, 15 .9 .199920 .30 .0
1KP-99-22-49Machner, H.Test of Charge Independence in p+d--*(A=3)+Pion ReactionsPAN1C 99, Uppsala, Schweden, 12 .6 .199920 .45 .0
IKP-99-22-50Machner, H.Test of Isospin Symmetry in NN-An ReactionsMENU 99, Zuoz, Schweiz, 15 .-20.8 .199920 .45 .0
IKP-99-22-51Machner, H.Meson Production in p+d ReactionsSTORI 99, Bloomington, IN, USA, 12 .9 .199920 .45 .0
1KP-99-22-52Machner, H.Empirische Zusammenhänge bei Reaktionen an derMesonenerzeugungsschwelleArbeitstreffen, Bad Honnef, 28 .10 .199920 .45 .0
IKP-99-22-53Maier, R.Protonenbeschleuniger - Ein ÜbersichtsvortragStudientage, Adenau, 10 .12 .199920 .30 .0
IKP-99-22-54Maier, R.Ausbaumöglichkeiten für COSYCANU-Arbeitstreffen, 20 .12 .199920 .30 .0
1KP-99-22-55Mihailescu, L.Experimental Observation of Bended Trajectories of the ChargeCarriers Inside a Segmented Closed-End Ge-DetectorTMR Working Group Meeting, Padua, Italy, 7.6.199920 .10 .0
IKP-99-22-56Mihailescu, L.Study of Algorithms to Extract Timing Information from SampledSignalsTMR Working Group Meeting, Padua, 1taly, 7 .6 .199920 .10 .0
IKP-99-22-57Mihailescu, L.On-Line Pulse Shape Analysis Algorithms for Tracking DetectorsEUROBALL Workshop, Strasbourg, France, 28 .11 .199920 .10 .0
1KP-99-22-58Moskal, P . (for the COSY-11 Collaboration at COSY)Heavy Meson Production at COSY-11STORI '99, Bloomington, IN, USA, 12 . - 16.9 .1999920 .45 .0
IKP-99-22-59Nünighoff, K.Entwicklung eines sehr leichten Spur-DetektorsVerhandlungen der DPG, Freiburg, 20 . - 26 .3 .199920 .50 .0
1KP-99-22-60Nünighoff, K .:A Light Straw Tracker Detector Working in Vacuum5th International Conference an Position-Sensitive Detectors, Univ.College London, United Kingdom, 13 . - 17 .9 .199920 .48 .0
1KP-99-22-61()eiert, W.Physik zum AntiwasserstoffFortbildungskurs für PhysiklehrerJülich, 9 .2 .199920.45.0
IKP-99-2262-Oelert, W.Das Antiwasserstoffexperiment am CERN und seine ZukunftIMEP Wien, Akademie der Wissenschaften, 12 .2 .199920 .45 .0
«KP-99-22-63()eiert, W.Schwellenphysik am COSY JülichVerhandlungen der DPG, Freiburg, 20 . - 26 .3 .199920 .50 .0
239
!KP-99-22-64Oelert, W.From Light to Heavy Hyperon-Antihyperon ProductionWorkshop an Future Perspectives of Physics with CooledAntiproton Beams, Rauischholzhausen, 9 .4 .199920 .50 .0
!KP-99-22-65Oelert, W.Threshold Production at COSY in Proton-Proton ScatteringPAC-TSL-Uppsala, 23 .4 .199920 .45 .0
IKP-99-22-66Oelert, W.Antimaterie - Physik im SpiegelbildDPG Lehrerfortbildung, Bad Honnef, 23 .6 .199920.50.0
1KP-99-22-67()eiert, W.Threshold Strangeness Production in pp-InteractionsTAPS '99 Collaboration Workshop, REZ!Prague, 4 . - 8 .9 .199920 .50 .0
IKP-99-22-68Oelert, W.Pläne am CERN - Taten an COSYSommerstudentenseminar, Jülich, 17 .9.199920 .45 .0
IKP-99-22-69Oelert, W.Schwellennahe Produktion neutraler Mesonen anCOSY-11Arbeitstreffen, Bad Honnef, 27 .10 .199920 .45.0
1KP-99-22-70Oelert, W.Schwellennahe Produktion neutraler Mesonen anCOSY-11Gemeinsames Seminar DFG Schwerpunkt ELSA und SFB 443,Bad Honnef, 27 . - 28 .10 .199920.45 .0
IKP-99-22-71Geiet, W.Antimaterie - ergänzendes oder widersprüchliches Phänomen?10. Auricher Wissenschaftstage 1999 - Forum einer dritten Kultur,Aurich, 12 .11 .199920.50.0
IKP-99-22-72Oelert, W.COSY und Schwellenphysik an COSY-11Keil . Universität Gießen, 18 .12.199920 .45 .0
!KP-99-22-73Probst, H . J.Gerätetechnischer Strahlenschutz und Sicherheitsmaßnahmen;Spezialkurs für Beschleunigerstrahlenschutz,RWTH Aachen, Haus der Technik, Essen, 13 .-16.9 .199920 .30 .0
IKP-99-22-74Probst, H . J.Betriebsinterne
Überwachung
und
Kontrollen,
Wartung,Aufzeichnungen und Meldepflichten;Spezialkurs für Beschleunigerstrahlenschutz,RWTH Aachen, Haus der Technik, Essen, 13 .-16.9 .199920.30 .0
IKP-99-22-75Probst, H . J.Arbeitsabläufe und Strahlenschutzplanung;Spezialkurs für Beschleunigerstrahlenschutz,RWTH Aachen, Haus der Technik, Essen, 13 .-16 .9 .199920.30 .0
IKP-99-22-76Razen, B . für die GEM-KollaborationDie Reaktion p+d--e3 He und p+d-a3 H+ff + in der übergangsregionVerhandlungen der DPG, Freiburg, 20 . - 26.3 .199920 .45 .0
IKP-99-22-77Ruderburg, E.Kaonproduktion am COSY-TOFArbeitstreffen, Bad Honnef, 27 .10 .199920 .45 .0
IKP-99-22-78Rossewij, M .J.Implementation of the Pulse Processing Analog to Digital Converterinto a PC EnvironmentTMR Working Group Meeting, IReS Strasbourg, France, 12 .2 .199920 .10 .0
IKP-99-22-79Rossewij, M .J.Communication Software Developments for the Pulse ProeessingAnalog to Digital ConverterTMR Working Group Meeting, Padua, Italy, 7 .6 .199920 .10 .0
IKP-99-22-80Schaal, H .:Shielding Calculations and Experiments6th ESS General Meeting, Ancona, Italy, Sept . 20-23, 199920 .48 .0
IKP-99-22-81Schäfer W.Nichtperturbative Effekte in den Seequarkverteilungen und die
d - ü AsymmetrieDPG-Frühjahrstagung, Freiburg, Germany, 25 .3 .199920 .80 .0
IKP-99-22-82Schäfer W.Die Spinstrukturfunktion gLT des ProtonsDPG-Frührjahrstagung, Freiburg, Germany, 25 .3.199920 .80 .0
IKP-99-22-83Schepers, G . (for the ATRAP-Collaboration at AD/CERN)Test von Detektorkomponenten für den ASPIRIN-Detektor amExperiment ATRAPVerhandlungen der DPG, Freiburg, 20 . - 26.3 .199920 .45 .0
IKP-99-22-84Schepers G . (for the COSY-11 Collaboration at COSY/Jülich)Vektormesonenproduktion in den Reaktionen ppt->ppo.)(e) amExperiment COSY-11Verhandlungen der DPG, Freiburg, 20 . - 26 .3 .199920 .45 .0
!KP-99-22-85Schulte-Wissermann, M.Entwicklung eines monolithischen Startdetektors mit segmentierterAuslese für das Flugzeitspektrometer an TOFVerhandlungen der DPG, Freiburg, 20 . - 26 .3 .199920 .45 .0
240
IKP-99-22-86Sewerin, S . (for the COSY-11 Collaboration at COSY/Jülich)Near Threshold Hyperon-Production at COSY-11 in the Ractionspp--apWA and pp-->pK410XVth Particles and Nuelei Int . Cont. PANIC, Uppsala, Sweden,10 . - 16 .6 .199920 .45 .0
IKP-99-22-87Speth J.Pion-Nucleon ScatteringUniversity of Adelaide, Adelaide, Australia, 12 .2 .1999Eiinders University, Adelaide Australia, 18 .2 .199920 .80 .0
IKP-99-22-88Speth J.Zurück in die Zukunft : Mesonen in der Kern- und TeilchenphysikUniversität Tübingen, 23.6 .199920 .80 .0
IKP-99-22-89Speth J.Pion-Nucleon Scattering and the Structure of the NucleonNew York City University, New York, USA, 3 .12 .199920 .80 .0
IKP-99-22-90Speth J.Meson Production at ThresholdsUniversity of Connecticut, Stoffs, USA, 6 .12 .199920 .80 .0
IKP-99-22-91Speth J.Meson Production at ThresholdsSUNY, Stony Break, USA, 9 .12 .199920 .80 .0
IKP-99-22-92Tietze, A .:Energy Deposition in Thick Targets6 eh ESS General Meeting, Ancona, Italy, 20 . - 23 .9 .199920.48 .0
!KP-99-22-93Wirth, S.Assoziierte Strangeness Produktion an COSY-TOFVerhandlungen der DPG, Freiburg, 20 . - 26.3 .199920 .45 .0
IKP-99-22-94Wolke, M . (for the COSY-11 Collaboration at COSY)Hyperen and Charged Kam Pair Production Close to ThresholdA u' Int . Cent on Physics at Storage Rings, Bloomington, IN, USA,12 . - 16 .9 .199920 .45 .0
IKP-99-22-95Wolke, M.Schwellennahe Strangeness-Produktion in der p-p Wechselwirkungan COSY-11Arbeitstreffen Mittelenergiephysik, Endingen, 4 . - 8 .10 .199920 .50 .0
IKP-99-22-96Wolke, M.Produktion offener StrangenessArbeitstreffen, Bad Honnef, 27 .10 .199920 .50 .0
IKP-99-22-97Zychor, 1.Measurements of the A hyperen lifetime in heavy hypemuclel atCOSY Jülich20 .50.0
Poster
!KP-99-23-1Baldauf, R ., Kleines, H ., Koch, N., Koptev, V ., Kovalev, A .,Lorenz, S., Mikirtytchiants, M ., Nekipelov, M ., Nelyubin, V ., Paetzgen. Schieck, H ., Rathmann, F .,
Sarkadi, J ., Seyfarth, H.,Steffens, E ., Vassiliev,
Zweit K. für die ANKE-Kollaboration:Intensity measurements at the ANKE ABSDPG-Frühjahrstagung, Physik der Hadronen und Kerne, Freiburg,22. - 26.3 .199920 .45 .0
IKP-99-23-2Baldauf, R ., Kleines, H., Koch, N ., Koptev, V ., Kovalev, A .,Lorenz, S ., Mikirtytchiants, M ., Nekipelov, M g Nelyubin, V ., Paetzgen . Schieck, H ., Rathmann, F., Sarkadi, J ., Seyfarth, H .,Steffens, E., Vassiliev, A ., Zvvoll, K . für die ANKE-Kollaboration:Degree of dissociation measurements at the ANKE ABSDPG-Frühjahrstagung, Physik der Hadronen und Kerne, Freiburg,22 . - 26.3 .199920 .45 .0
IKP-99-23-3Baldauf, R ., Kleines, H, Kravtsov, P ., Mikirtytchiants, M.,Nekipelov, M ., Rathmann, F., Sarkadi, J ., Seyfarth, H ., Vassiliev, A.and Zwoll, K .:The Slow Control System for the ANKE ABSInt .Workshop en Polarized Sources and Targets (PST99),Erlangen, 29 .9 . - 2 .10 .199920 .45 .0
KP-99-23-4Brüggemann, R ., Koptev, V ., Kravtsov, P ., Lemaitre, S ., Lorenz, S .,Nelyubin, V., Rathmann, F., Paetz gen . Schieck, H ., Seyfarth, H .,Steffens, E ., Vassiliev,High Field Permanent Sextupole Magnets for the ANKE ABSInt .Workshop on Polarized Sources and Targets (PST99),Erlangen, 29 .9 . - 2 .10 .199920 .45 .0
IKP-99-23-5Eversheim, P . D . ; Felden, 0 . ; Gebel, R . ; Glende, M .;The Storage Gell for the EDDA-Experiment at COSYPST 99, Erlangen, 28.9 . - 1 .10 .199920 .38 .0
IKP-99-23-6Eversheim, P . D . ; Felden, 0 . ; Gebel, R . ; Glende, MgThe Control System of the polarized Ion Source at COSY-JülichPST 99, Erlangen, 28.9. - 1 .10.199920 .38 .0
IKP-99-23-7Gast, W., Brands, H . . Georgiev, A ., Jäger, H .M ., Lieder, R .M .,Mihailescu, L ., Rossewij, M ., Stein, J.Implementation of the Pulse Processing Analog to Digital Converterinto a PC EnvironmentVerhandlungen der DPG, Freiburg, 20 .-26 .3 .199920.10.0
IKP-99-23-8Koch, N ., Koptev, V ., Kovalev, A ., Kravtsov, P ., Mikirtytchiants, M .,Nekipelov, M., Nelyubin, Rathmann, F., Seyfarth, H.,Vassiliev, A .:Degree of dissociation measurements on the ANKE ABS beamInt .Workshop on Polarized Sources and Targets (PST99),Erlangen, 29 .9 . - 2 .10.199920 .45 .0
IKP-99-23-9Koptev, V .,
Kovalev, A .,
Kravtsov, P .,
Mikirtytchiants, M .,Nekipelov, M ., Rathmann, F., Seyfarth, H ., Vassiliev, A.:Compression Tube Measurements of the ANKE ABS beamintensityInt.Workshop on Polarized Sources and Targets (PST99),Erlangen, 29 .9 . - 2 .10.199920 .45 .0
241
IKP-99-23-10Lieder, R .M., Rzaca-Urban, T ., Brands, H ., Gast, W ., Jäger, H .M.,Mihailescu, L, Pytel, Z ., Urban, W ., Morek, T., Droste, Chr ., Chmel,S ., Bazzacco, D ., Falconi, G ., Menegazzo, R ., Lunardi, S., Rossi-Alvarez, C ., de Angelis, G ., Famea, E ., Gadea, A ., Neon, D.R,,Podolyak, Z.Investigation of Magnetic Rotational Bands in 142 Gd withEUROBALLProc . EUROBALL Workshop ,,Physics and Perspective using theEUROBALL IV Spectrometer, Strasbourg, 199920 .10 .0
IKP-99-23-11Mihailescu, L, Brands, H ., Gast, W ., Lieder, R .M., Rossewij, M.The Importance of the Anisotropy in the Dritt Velocity for theDevelopment of Ge y-Ray Tracking DetectorsVerhandlungen der DPG, Freiburg, 20 . - 26,3 .199920 .10 .0
1KP-99-23-12Nünighoff, K . ; Fanara, C . ; Filges, D . ; Geyer, R . ; Kilian, K .;Roderburg, E . ; Schmitz, M .:A Light Straw Tracker Detector Working in Vacuum5th International Conference on Position-Sensitive Detectors, Univ.College London, United Kingdom, Sept . 13-17, 199920 .48 .0
IKP-99-23-13Schnase, A . ; Boehnke, M . ; Etzkom, F .-J . ; Maier, R . ; Rindfleisch,U . ; Stockhorst, H.Broadband synchrotron cavity for COSY with minimum size basedon VitroPermPAC 99, New York, USA, 29 .3 . - 2 .4.199920 .30 .0
Patents
1KP-99-31-1Berst, M. Eberth, J ., Jäger, H .M., Kämmerling, H ., Lieder, R .M .,Renftle, W.Verfahren zum Herstellen eines gekapselten DetektorsPT 1 .1148 GEP : 0710365 (22 .9 .1999)20 .10 .0
IKP-99-31-2Heinrichs, G . ; Meuth, H . ; Schnase, A . ; Stockhorst, H.Schmalbandiger arbiträrer HF-Modulations- und RauschgeneratorEuro-PCT-Anmeldung 95 902 757 .4-2204Die amerikanische Version dieses Patents ist bereits unter derNummer 5694094 erteilt.20 .30 .0
Application for a Patent
IKP-99-32-1Gast, W ., Georgiev, A ., Südholt, R ., Rose, Th.Zeit-zu-Digital-Umsetzer basierend auf der Vernier-Interpolationund KorrelationsprinzipienPT 1 .1745DE : 199 52 370.3 (30.10 .99)20 .10 .0
242
IKP-99-4-5Lieder, FL M.Kernphysikalische Methoden in Natur, Umwelt und MedizinUniversität Bonn20 .10 .0
IKP-99-4-6Maier, R.Teilchenbeschleuniger 1Universität Bonn20 .30 .0
IKP-99-4-7Meißner Ulf-G.Theoretische ElektrodynamikUniversität Bonn, V4, U41 .1 KPH
IKP-99-4-8Rathmann, F.Physik für MedizinerUniversität Erlangen-Nürnberg, Lt- 2
IKP-99-4-9Speth J.Theoretische ElektrodynamikUniversität Bonn, V4, U41 .1 KPH
1KP-99-4-10Ströher, H.Einführung in die Physik UI (Optik)
IKP-99-4-11Wirzba A.Nichtlineare Dynamik und deterministisches ChaosTechnische Universität Darmstadt, V2, UI1 .1 KPH
Lectures at Universities
WS 98/99
IKP-99-4-1Filges, D.Physik 111, Kernphysik, ThermodynamikUniversität Wuppertal, V2, U21,1 KPH11 .4 ESS,
SS 99
1KP-99-4-2Baur G.Einführung in das Standardmodell der Elementarteilchenphysik, ViUniversität Basel1 .1 KPH
IKP-99-4-3Filges, D.Ausgewählte Kapitel des StrahlenschutzesUniversität Wuppertal, V214 ESS
1KP-99-4-5Krewald S.Einführung in die Theorie der schwachen WechselwirkungUniversität Bonn, V21 .1 KPH
IKP-99-4-6Meißner Ulf-G.Thermodynamik und StatistikUniversität Bonn, V4, U41 .1 KPH
1KP-99-4-7Rathmann, F.Ausgewählte Kapitel der Spin-Physik (mit Exkursion)Universität Erlangen-Nümberg, V 1
IKP-99-4-8Speth J.Thermodynamik und StatistikUniversität Bonn, V4, U41 .1 KPH
IKP-99-4-9Ströher, H.Einführung in die Physik 11 (Elektrizitätslehre)
WS 1999/2
IKP-99-4-1Baur G.Neutrinos in Teilchenphysik und AstrophysikUniversität Basel, Vl1 .1 KPH
1KP-99-4-2Berthen, G ., Sistemich, K " Ströher, H.Oberseminar Kernphysik, V2Universität zu Köln
IKP-99-4-3Filges, D.Seminar über Abschirmprobleme von Teilchen-beschleunigernUniversität Wuppertal, V21 .4 ESS
IKP-99-4-4Krewald S.Einführung in die QuantenelektrodynamikUniversität Bonn, V21 .1 KPH
243
244
XI. 1 . 1 E X OF AUTORS
COS Y-11-Collaboration
40,41,42,43,44,47,48,49,50,51
ANKE-Collaboration
15COSY-GEM-Collaboration
55,57,58,60,161
COSY-EDDA-Collaboration
62,65,COSY-TOF-Collaboration
5,7,8,10,11,14
COSY-MOMO-Collaboration
161JESSICA-Collaboration
174
Abdel-Samad, S . 12 Büttiker, P . 95Ackens, A . 74 But, J . 71Adam, H. H. 20,50,52 Butzek, M. 174AIkhazov, G.D . 177 Cassing, W . 25Anagnostopoulos, D . 72 Chatellard, D . 72Angelis, de G . 79,80,81,84 Chernetsky, V . 35Augsburger, M . 72 Chernyshev, V . 24,35,122Augustyniak, W . 177 Chiladze, B . 29Baldauf, R . 36 Chmel, S . 79B
ert-Wiemer, H . 174 Clemens, U. 74Barsov, S . 21,22,31, Clement, H . 5Baru, V . 113,122,123, Conin, L . 152Baur, G . 124,125,126,127,136, Conrad, H. 174
137 Cugnon, J . 181Bazzacco, D. 79,80,81,84 Daemen, J . 5Bechstedt, U. 143,144,152 Dahmen, B . 157,181Beck, R . 34 De
rörs, L . 9Bellemann, F. 66 Derissen, W . 157,161Berg, A . 66 Deutsch, C . 181Bernard, V . 97,102 Dewald, A . 22,80Bertulani, Z .A . 137 Dietrich, J . 143,144,146,149,184Bilger, R . 5 Döring, K . 5,34Bisplinghoff, J . 62,66,157 Dolfus, N . 12,73,152,198Bohlscheid, G . 66 Dolzi, D . 137Böhm, A . 9 Drechsel, D. 111Böhnke, M . 150 Drochner, M . 30Bojowald, J . 71,146,149,196,198 Droste, C . 79,81,84Bongardt, K. 184,185,188 Ducret, J.E . 177Borchert, G .L . 18,19,29,72,196 Dymov, S .N. 18,19Borgs, W . 35 Egger, J .-P . 72Borsch, H. 153 El
oury, P . 72Boudard, A . 177 Emmerich, R . 39Boukharov, A . 35 Enge, R . 152,157Bräutigam, W . 184 Engel, J . 161Brands, H. 79,81,83,84 Engels, R . 36,39Bratkovskaya, E. 25 Enke, M . 171,172,173Bin
ann, K.T. 9,10 Epelbaum, E . 98,100Brökel, E . 198 Erhardt, A . 5Budzanowski, A . 176 Ernst, J . 66Büscher, M . 15,16,18,19,24,25,26, Ernst, W . 198
35,114 Erven, W . 71Eßer, R . 28,29
245
Etzkorn, F.-J . 150 Jansen, H. 71Eversheim, P.D . 65,157 Jarczyk, L 66,176Eyrich, W. 7 Jensen, HJ . 80,81Faber, P. 152,157 Joosten, R . 66Falconi, G . 79,84 Junghans, H. 16F
ea, E . 79,81,84 Kacharava, A . 18,19,29Fe
' ng, H. W . 112 Kamerdzhiev, S . 133Felden, 0 . 65,157 Kamys, B . 176Fettes, N. 91,97 Kämmerling, H. 5Filges, D . 5,6,171,172,173,174, Kamadi, M . 197
176,177 Karsch, L . 9Fiori, G. 195,196 Kasemann, S. 80Firmenich, H 71 Khoukaz, A . 20,50,52Fleischer, N . 5 Kilian, K . 5,6,12,176,177Frehaut, J . 177 Kirch, K . 72Freiesleben, H. 9 Kistryn, M . 176Gad, N. 157 Kistryn, S . 176Gadea, A . 79,81,84 Klein, R . 5,12Galin, J . 171,172,173 Kleines, H. 36Gasp
an, A . 113,115 Klemt, V . 135Gast, W . 79,80,81,82,83,84 Kluge, HJ . 196Gebel, R . 65,143,144,157 Knöchlein, G . 111Gehsing, D . 181 Koch, H .R. 28,29,36Gellas, G. C . 108,109,110 Köhler, M. 71Georgiev, A . 83 Komarov, V .I . 18,19,29Geyer, R . 6 Kondratyuk, L . 24,25,114,115Glende, M . 65,157 Koptev, V . 16,26,36Glockle, W . 98 Kovalev, A . 36Göbbels, J . 165 Kowina, P . 47,51Goldenbaum, F. 171,172,173,174,177 Kozela, A . 66Gorke, H . 74 Kozhuharov, C . 196Gotta, D. 72,73,74 Krafft, K . 165Grishina, V . 25,26,114 Kravtsov, P. 36,177Grzonka, D . 47,71 Krebs, H . 102Hadamek, H. 5,71,157 Krehl, 0 . 116,118,120,128Haidenbauer, J . 53,113,114,115, Kremer, M . 71.
123 Kress, J . 5Haft, B . 174 Krewald, S . 116,118,120,128,Halabuka, Z . 126 130Hamacher, A. 195,196 Krings, T . 195,196Hanhart, Ch . 115,116 Krol, G . 152Hansen, G . 5,174 Kruck, K . 161Hauser, P . 72 Ktorides, C. N. 109,110Heim, T.A. 127 Kubis, B . 89,93,94Hejny, V . 26,27,34 Kudryavtsev, A . 113,122Hemmert, T .R . 93,94,108,109,110, Kueven, M . 71
111,112 Kuhlmann, E . 14Heticken, K. 124,125,126,127,136 Kulikov, A.V . 29Henn, K . 143,144 Kurbatov, A. 18,19Hennebach, M. 28,29 Labus, H . 12,73,198Herbach, C . 171,173 Lang, N. 20,52Hilscher, D. 171,172,173 Langenberg, G . 152Hinterberger, F. 62,66 Lawin, H. 149Holona, M. 71 Ledoux, X. 177Holstein, B . R . 111 Lehmann 21,22Ibald, R . 66 Lehrach, A . 143,144Indelicato, P . 72 Leray, S . 177Iv,ov, L 121 Letchford, A. 185Jach, K.D . 152 Letourneau, A. 171,172,173Jäger, H.M . 79,80,81,84 Lewis, R . 112Jahn, R . 66,161 Ley, J . 39Jahnke, U . 171,172,173 Lieder, R . M . 79,80,81,82,84Ja
n, M. 106 Lister, Th . 20,41,50,52
246
Loevenich, H . 74 Petrache, C .M. 80,81Lorentz, B . 36,143,144 Petrus, A .Yu . 29Lorenz, S . 36 Pfeiffer, J . 195Lott, B . 171,172,173 Pich, A . 106Lunardi, S . 79,80,81,84 Pienkowski, L . 171,173Lürken, G . 198 Podoliyak, Z . 79,81,84Macharashvili, G.G . 29 Pohl, C . 165,174Machner, H . 53,66,161,176 Pras, P . 177Maeckelburg, D. 74 Prasuhn, D . 143,144,147Magiera, A . 66,176 Probst, H .J . 165Maier, R . 143,144,147,161,184 Prokofiev, A.N . 177Marcinkowska, Z . 80 Pronyaev, A . V. 121Marcinkowski, R . 80 Protic, D . 21,31,195,196Martin, S . 184 Pütz, H . 152Marwinski, S. 11 Pysz, K . 176Maschuw, R . 66 Pytl, Z. 79,81,84Mayer-Kuckuk, T . 66 Quentmeier, C . 20,41,52Medina, N.H . 80 Ra
i
ov, A . 101Meier, H. 126 Ramm, M . 74Meißner, U.-G. 89,91,92,93,94,95,96, Ramos, A . 107
97,98,100,101,102, Rathmann, F . 36109,110 Rejmund, M . 80
Meixner, C . 5 Renftle, W . 5Menegazzo, R . 79,81,81,84 Rho, M . 103,104,105Mertler, G. 66 Richert, A . 181Merzliakov, S . 21,31,33 Rindfleisch, U . 150,157Metz, H . 195,196 Roderburg, E . 5,177Migdal, W . 176 Rogozik, B . 152Mihailescu, L . 79,81,82,84 Rongen, H . 73Mikirtichyants, M. 36 Rosendaal, D . 66,157Mikirtichyants, S . 21,36 Rossen, v . P . 66,143,144,157,161,Mohos, I . 146,149,196 184Mojzis, M. 91 Rossewij, M . J . 82,83Morek, T . 79,81,84 Rossi-Alvarez, C . 79,80,81,84Morsch, H.P. 75,177 Rotert, N . 157Moskal, P . 42,43,44,51 Ruhrig, D . 152Müller, A . 157 Rzaca-Urban, T . 79,80,81,84Müller, G . 92 Sagefka, Th . 152,157Müller, H . 18,27 Santo, R. 20,52Müskes, M . 152 Sarkadi, J . 36Munkel, J . 66, Schaaf, M . 181Mussgiller, A . 21,30,31,33 Schaal, H . 165,171,172,173,177Napoli, D.R . 79,80,81,84 Schäfer, W . 121Neef, R .-D. 171,172,173,174,177 Schapiro, O . 171Nekipelov, M . 36 Scheiba, F . 152Neilen, R . 71,198 Schepers, G . 47,71Nelyubin, V .V . 36 Schleichen, R . 21,22,30,31,33Neumann-Cosel, v . P . 66 Schmitz, Jo . 71Nikolaev, N.N . 108,121 Schmitz, M. . 6Nioradze, M.S . 29 Schnase, A . 143,144,150,184Novotny, R . 34 Schneider, H. 143,144Nünighoff, K . 6,171,172,173 Schnitker, H. 66Oelert, W . 71 Schroeder, U . 173Oller, J .A . 96,106,107 Schug, G . 181Oset, E . 107 Schultheiß, F . 71Pabst, M . 185 Scobel, W . 9,62Paetz gen. Schieck, H . 36,39 Sefzick, T . 71Park, B .-Y . 103 Sewerin, S . 40Pastemak, A . 80 Seyfarth, H . 36Patin, P. 177 Shuryak, E . 105Paul, N . 5,171,172,173,174 Siems, Th . 72Pavan, P . 80 Simons, L.M . 72Peghaire, A . 171,172,173 Singer, H. 157,181
247
Sisternich, K. 15Smyrski, 48,49,66Sobotta, K . 181Speth, J . 113,114,115,116,
118,120,123,128,130,133
Spölgen, D . 71Stagnoli, P . 124Stassen, R. 143,144,181Stechemesser, H . 5Steffens, E . 36Stein, HJ. 83,147Steinert, L. 22Steininger, S . 91Stelzer, H . 174Sterzenbach, G. 171,172,173Stockhorst, H . 14,143,144,150Stöhlker, T . 196Strehl, J . 71Ströher, H . 26,34Strokovsky, E.A. 177Strzalkowski, A . 66Sun, G. 9Tarasov, V . 122Teilten, Y . 177Tertychny, G. 133Tietze, A . 171,172,173Tietze-Jaensch, H . 174Tölle, R . 66,143,144,161,184Toke, J . 173Trautmann, D. 124,125,126,127,136T
el, S . 136Ullmaier, H. 174Urban, W . 79,80,81,84Utzelman, S . 80Vassiliev, A . 36Venkova, T. 81Verhoeven, W . 52Volant, C . 177Wang, Z . 130Watzlawik, K.H. 197Wilms, A . 8Wirzba, A . 103,104,105Witt, J .D . 147Wolke, M. 41Wolter, H.H. 136Wüstner, P . 30,48,71Wyrwich, H. 5Wyss, R. 81Y
siev, U. 101Yaschenko, S .V . 18,19Zahed, I . 103,104,105Zaplatin, E . 181,184Zhu, L . 80Zupranski, P. 75,177Zwoll, K . 36,71,74Zychor, L 23
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